PRENATAL CARE IN THE UNITED STATES
DIAGNOSIS OF PREGNANCY
INITIAL PRENATAL EVALUATION
SUBSEQUENT PRENATAL VISITS
As described by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012), “A comprehensive antepartum program involves a coordinated approach to medical care, continuous risk assessment, and psychological support that optimally begins before conception and extends throughout the postpartum period and interconceptional period.” Optimizing the health and well-being of women before pregnancy should logically be an integral prelude to prenatal care. Adequate and appropriate preconceptional care, as discussed in detail in Chapter 8, has the potential to assist women by reducing risks, promoting healthy lifestyles, and improving readiness for pregnancy.
PRENATAL CARE IN THE UNITED STATES
Almost a century after its introduction, prenatal care has become one of the most frequently used health services in the United States. In 2001, there were approximately 50 million prenatal visits. The median was 12.3 visits per pregnancy, and many women had 17 or more total visits. This information is gathered from birth certificates, and a revised form was introduced in 2003. It is now used by 27 states and Puerto Rico, whereas the remaining 23 states continue to use a 1989 form. Unfortunately, data regarding the timing of prenatal care from these two systems are not directly comparable (Osterman, 2011).
Since the early 1990s, the largest gains in timely prenatal care have been among minority groups. As shown in Figure 9-1, however, disparity continues. Of the 27 states using the revised birth certificate, the percentage of non-Hispanic white, Hispanic, and African-American women who received no prenatal care in 2008 was 1.1, 2.7, and 3.3, respectively (Osterman, 2011). Some of the obstetrical and medical risk factors or complications identifiable during prenatal care are summarized in Table 9-1. Importantly, many of these complications are treatable.
FIGURE 9-1 Percentage of women in the United States with prenatal care beginning in the first trimester by ethnicity in 1989, 2001, and 2006. (Adapted from Martin, 2002b, 2009.)
TABLE 9-1. Obstetrical and Medical Risk Factors Detected During Prenatal Care in the United States in 2001
Assessing Prenatal Care Adequacy
A commonly employed system for measuring prenatal care adequacy is the index of Kessner and colleagues (1973). This Kessner Index incorporates three items from the birth certificate: length of gestation, timing of the first prenatal visit, and number of visits. Although it does not measure the quality of care, the index remains a useful measure of prenatal care adequacy. Using this index, the National Center for Health Statistics concluded that 12 percent of American women who were delivered in 2000 received inadequate prenatal care (Martin, 2002a).
The Centers for Disease Control and Prevention (2000) analyzed birth certificate data for the years 1989 to 1997 and found that half of women with delayed or no prenatal care wanted to begin care earlier. Barriers to care varied by social and ethnic group, age, and payment method. The most common reason cited was late identification of pregnancy by the patient. The second most commonly cited barrier was lack of money or insurance. The third was inability to obtain an appointment.
Prenatal Care Effectiveness
Care designed during the early 1900s focused on lowering the extremely high maternal mortality rate. Such care undoubtedly contributed to the dramatic decline in this rate from 690 per 100,000 births in 1920 to 50 per 100,000 by 1955 (Loudon, 1992). As discussed in Chapter 1 (p. 5), the relatively low current maternal mortality rate of approximately 10 to 15 per 100,000 is likely associated with the high utilization of prenatal care (Xu, 2010). Indeed, in their analysis of data from 1998 to 2005 from the Pregnancy Mortality Surveillance System (PRAMS), Berg and associates (2010) identified a fivefold increased risk for maternal death in women who received no prenatal care.
There are other studies that attest to the efficacy of prenatal care. Herbst and colleagues (2003) found that lack of prenatal care was associated with more than a twofold increased risk of preterm birth. National Center for Health Statistics data showed that women with prenatal care had an overall stillbirth rate of 2.7 per 1000 compared with 14.1 per 1000 for women without prenatal care (Vintzileos, 2002a). These same investigators later reported that prenatal care was associated with lower rates of preterm birth as well as neonatal death associated with placenta previa, fetal-growth restriction, and postterm pregnancy (Vintzileos, 2002b, 2003). Evaluating the format of care, Ickovics and associates (2007) compared individual prenatal care and group prenatal care. The latter provided traditional pregnancy surveillance in a group setting with special focus on support, education, and active health-care participation. Women enrolled in group prenatal care had significantly reduced preterm birth rates compared with those receiving individual care.
DIAGNOSIS OF PREGNANCY
Pregnancy is usually identified when a woman presents with symptoms and possibly a positive home urine pregnancy test result. Typically, such women receive confirmatory testing of urine or blood for human chorionic gonadotropin (hCG). Further, there may be presumptive or diagnostic findings of pregnancy during examination. Sonography is often used, particularly if miscarriage or ectopic pregnancy is a concern.
Signs and Symptoms
The abrupt cessation of menstruation in a healthy reproductive-aged woman who previously has experienced spontaneous, cyclical, predictable menses is highly suggestive of pregnancy. As discussed in Chapter 5 (p. 80), menstrual cycles vary appreciably in length among women and even in the same woman. Thus, amenorrhea is not a reliable pregnancy indicator until 10 days or more after expected menses. Occasionally, uterine bleeding occurs after conception and can be somewhat suggestive of menstruation. During the first month of pregnancy, such episodes are likely the consequence of blastocyst implantation. Still, first-trimester bleeding should generally prompt evaluation for an abnormal pregnancy.
During pregnancy, the vaginal mucosa usually appears dark-bluish red and congested—Chadwick sign, popularized by him in 1886. Although presumptive evidence of pregnancy, it is not conclusive. Also, there is increased cervical softening as pregnancy advances. Other conditions, however, such as estrogen–progestin contraceptives, may cause similar softening. As pregnancy progresses, the external cervical os and cervical canal may become sufficiently patulous to admit a fingertip, but the internal os should remain closed.
The substantial increase in progesterone secretion associated with pregnancy affects the consistency and microscopic appearance of cervical mucus. Specifically, microscopic observation of a fernlike pattern of mucus, which is typically seen in the midportion of the menstrual cycle, makes pregnancy unlikely (Fig. 4-2, p. 49).
During the first few weeks of pregnancy, uterine size grows principally in the anteroposterior diameter. During bimanual examination, it feels doughy or elastic. At 6 to 8 weeks’ menstrual age, the firm cervix contrasts with the now softer fundus and the compressible interposed softened isthmus—Hegar sign. Isthmic softening may be so marked that the cervix and uterine body seem to be separate organs. By 12 weeks’ gestation, the uterine body is almost globular, with an average diameter of 8 cm.
In later pregnancy, using a stethoscope for auscultation, one may hear the uterine souffle. This is a soft, blowing sound that is synchronous with the maternal pulse. It is produced by the passage of blood through the dilated uterine vessels and is heard most distinctly near the lower portion of the uterus. In contrast, the funic souffle is a sharp, whistling sound that is synchronous with the fetal pulse. It is caused by the rush of blood through the umbilical arteries and may not be heard consistently. Fetal heart tones can also be heard and are described on page 176.
Breast and Skin Changes
Anatomical changes in the breasts that accompany pregnancy are characteristic during a first pregnancy (Chap. 4, p. 50). These are less obvious in multiparas, whose breasts may contain a small amount of milky material or colostrum for months or even years after the birth of their last child, especially if the child was breast fed.
Increased pigmentation and visual changes in abdominal striae are common to, but not diagnostic of, pregnancy. They may be absent during pregnancy and may also be seen in women taking estrogen-containing contraceptives.
Maternal perception of fetal movement depends on factors such as parity and habitus. In general, after a first successful pregnancy, a woman may first perceive fetal movements between 16 and 18 weeks’ gestation. A primigravida may not appreciate fetal movements until approximately 2 weeks later. At about 20 weeks, depending on maternal habitus, an examiner can begin to detect fetal movements.
Detection of hCG in maternal blood and urine is the basis for endocrine assays of pregnancy. This hormone is a glycoprotein with high carbohydrate content. There are subtle hCG variants, and these differ by their carbohydrate moieties. The general structure of hCG is a heterodimer composed of two dissimilar subunits, designated α and β, which are noncovalently linked. As described in Chapter 5 (p. 101), the α-subunit is identical to those of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH). HCG prevents involution of the corpus luteum, which is the principal site of progesterone formation during the first 6 weeks of pregnancy.
Syncytiotrophoblast produce hCG in amounts that increase exponentially during the first trimester following implantation. With a sensitive test, the hormone can be detected in maternal serum or urine by 8 to 9 days after ovulation. The doubling time of serum hCG concentration is 1.4 to 2.0 days. As shown in Figure 9-2, serum hCG levels increase from the day of implantation and reach peak levels at 60 to 70 days. Thereafter, the concentration declines slowly until a plateau is reached at approximately 16 weeks.
FIGURE 9-2 Mean concentration (95% CI) of human chorionic gonadotropin (hCG) in serum of women throughout normal pregnancy.
Measurement of hCG
As noted, hCG is composed of both an α- and a β-subunit, but the β-subunit is structurally distinct from that of LH, FSH, and TSH. With this recognition, antibodies were developed with high specificity for the hCG β-subunit. This specificity allows its detection, and numerous commercial immunoassays are available for measuring serum and urine hCG levels. Although each immunoassay detects a slightly different mixture of hCG variants, its free subunits, or its metabolites, all are appropriate for pregnancy testing (Cole, 1998).
One commonly employed technique is the sandwich-type immunoassay. With this test, a monoclonal antibody against the β-subunit is bound to a solid-phase support. The attached antibody is then exposed to and binds hCG in the serum or urine specimen. A second antibody is then added, binds to another site on the hCG molecule, and “sandwiches” the bound hCG between the two antibodies. In some assays, the second antibody is linked to an enzyme, such as alkaline phosphatase. When substrate for the enzyme is added, a color develops. The color intensity is proportional to the amount of enzyme and thus to the amount of the second antibody bound. This, in turn, is a function of the hCG concentration in the test sample. The sensitivity for the laboratory detection of hCG in serum is as low as 1.0 mIU/mL using this technique. With extremely sensitive immunoradiometric assays, the detection limit is even lower (Wilcox, 2001).
False-positive hCG test results are rare (Braunstein, 2002). A few women have circulating serum factors that may bind erroneously with the test antibody directed to hCG in a given assay. The most common factors are heterophilic antibodies. These are produced by an individual and bind to the animal-derived test antibodies used in a given immunoassay. Thus, women who have worked closely with animals are more likely to develop such antibodies, and alternative laboratory techniques are available (American College of Obstetricians and Gynecologists, 2013a). Elevated hCG levels may also reflect molar pregnancy and its associated cancers (Chap. 20, p. 396). Other rare causes of positive assays without pregnancy are: (1) exogenous hCG injection used for weight loss, (2) renal failure with impaired hCG clearance, (3) physiological pituitary hCG, and (4) hCG-producing tumors that most commonly originate from gastrointestinal sites, ovary, bladder, or lung (Montagnana, 2011).
Home Pregnancy Tests
Millions of over-the-counter pregnancy test kits are sold annually in the United States. In one study, Cole and associates (2011) found that a detection limit of 12.5 mIU/mL would be required to diagnose 95 percent of pregnancies at the time of missed menses. They noted that only one brand had this degree of sensitivity. Two other brands gave false-positive or invalid results. In fact, with an hCG concentration of 100 mIU/mL, clearly positive results were displayed by only 44 percent of brands. As such, only about 15 percent of pregnancies could be diagnosed at the time of the missed menses. Some manufacturers of even newer home urine assays claim > 99-percent accuracy on the day of—and some up to 4 days before—the expected day of menses. But, careful analysis suggests that these assays are often not as sensitive as advertised (Cole, 2011).
Sonographic Recognition of Pregnancy
Transvaginal sonography has revolutionized early pregnancy imaging and is commonly used to accurately establish gestational age and confirm pregnancy location. A gestational sac—a small anechoic fluid collection within the endometrial cavity—is the first sonographic evidence of pregnancy. It may be seen with transvaginal sonography by 4 to 5 weeks’ gestation. A fluid collection, however, can also be seen within the endometrial cavity with an ectopic pregnancy and is termed a pseudogestational sac or pseudosac (Fig. 19-5, p. 382). Thus, further evaluation may be warranted if this is the only sonographic finding, particularly in a patient with pain or bleeding. A normal gestational sac implants eccentrically in the endometrium, whereas a pseudosac is seen in the midline of the endometrial cavity. Other potential indicators of early intrauterine pregnancy are an anechoic center surrounded by a single echogenic rim—the intradecidual sign—or two concentric echogenic rings surrounding the gestational sac—the double decidual sign (Fig. 9-3) (Chiang, 2004). If sonography yields equivocal findings—the so-called pregnancy of unknown location, then serial serum hCG levels can also help differentiate a normal intrauterine pregnancy from an extrauterine pregnancy or an early miscarriage (Chap. 19, p. 381).
Visualization of the yolk sac—a brightly echogenic ring with an anechoic center—confirms with certainty an intrauterine location for the pregnancy and can normally be seen by the middle of the fifth week. As shown in Figure 9-3, after 6 weeks, an embryo is seen as a linear structure immediately adjacent to the yolk sac, and cardiac motion is typically noted at this point. Up to 12 weeks’ gestation, the crown-rump length is predictive of gestational age within 4 days (Chap. 10, p. 195).
FIGURE 9-3 Transvaginal sonogram of a first-trimester intrauterine pregnancy. The double decidual sign is noted surrounding the gestational sac and is defined by the decidua parietalis (white asterisk) and the decidua capsularis (yellow asterisk). The arrow notes the yolk sac, and the crown-rump length of the embryo is marked with measuring calipers. (Image contributed by Dr. Elysia Moschos.)
INITIAL PRENATAL EVALUATION
Prenatal care should be initiated as soon as there is a reasonable likelihood of pregnancy. Major goals are to: (1) define the health status of the mother and fetus, (2) estimate the gestational age, and (3) initiate a plan for continuing obstetrical care. Typical components of the initial visit are summarized in Table 9-2. The initial plan for subsequent care may range from relatively infrequent routine visits to prompt hospitalization because of serious maternal or fetal disease.
TABLE 9-2. Typical Components of Routine Prenatal Care
Use of a standardized record within a perinatal health-care system greatly aids antepartum and intrapartum management. Standardizing documentation may allow communication and care continuity between providers and enable objective measures of care quality to be evaluated over time and across different clinical settings (Gregory, 2006). A prototype is provided by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) in their Guidelines for Perinatal Care, 7th edition.
There are several definitions pertinent to establishment of an accurate prenatal record.
1. Nulligravida—a woman who currently is not pregnant nor has ever been pregnant.
2. Gravida—a woman who currently is pregnant or has been in the past, irrespective of the pregnancy outcome. With the establishment of the first pregnancy, she becomes a primigravida, and with successive pregnancies, a multigravida.
3. Nullipara—a woman who has never completed a pregnancy beyond 20 weeks’ gestation. She may not have been pregnant or may have had a spontaneous or elective abortion(s) or an ectopic pregnancy.
4. Primipara—a woman who has been delivered only once of a fetus or fetuses born alive or dead with an estimated length of gestation of 20 or more weeks. In the past, a 500-g birthweight threshold was used to define parity. As discussed in Chapter 1 (p. 2), this threshold is now controversial because many states still use this weight to differentiate a stillborn fetus from an abortus. However, the survival of neonates with birthweights < 500 g is no longer uncommon.
5. Multipara—a woman who has completed two or more pregnancies to 20 weeks’ gestation or more. Parity is determined by the number of pregnancies reaching 20 weeks. It is not increased to a higher number if multiples are delivered in a given pregnancy. Moreover, stillbirth does not lower this number. In some locales, the obstetrical history is summarized by a series of digits connected by dashes. These refer to the number of term infants, preterm infants, abortuses younger than 20 weeks, and children currently alive. For example, a woman who is para 2–1–0–3 has had two term deliveries, one preterm delivery, no abortuses, and has three living children. Because these are nonconventional, it is helpful to specify the outcome of any pregnancy that did not end normally.
Normal Pregnancy Duration
The mean duration of pregnancy calculated from the first day of the last normal menstrual period is very close to 280 days or 40 weeks. In a study of 427,581 singleton pregnancies from the Swedish Birth Registry, Bergsjø and coworkers (1990) found that the mean pregnancy duration was 281 days with a standard deviation of 13 days.
It is customary to estimate the expected delivery date by adding 7 days to the date of the first day of the last normal menstrual period and counting back 3 months—Naegele rule. For example, if the last menstrual period began September 10, the expected date of delivery is June 17. However, a gestational age or menstrual age calculated in this way assumes pregnancy to have begun approximately 2 weeks before ovulation, which is not always the case.
Clinicians use this gestational age to mark temporal events during pregnancy. In contrast, embryologists and other reproductive biologists more often employ ovulatory age or fertilization age, both of which are typically 2 weeks earlier. Somewhat related, Bracken and Belanger (1989) tested the accuracy of various “pregnancy wheels” provided by three pharmaceutical companies and found that such devices predicted incorrect delivery dates in 40 to 60 percent of estimates, with a 5-day error being typical. As physicians and hospitals increasingly transition to electronic medical records, however, such errors should be largely obviated by more precise estimates of gestational age produced by calculator software applications.
It has become customary to divide pregnancy into three equal epochs of approximately 3 calendar months. Historically, the first trimester extends through completion of 14 weeks, the second through 28 weeks, and the third includes the 29th through 42nd weeks of pregnancy. Thus, there are three periods of 14 weeks each. Certain major obstetrical problems tend to cluster in each of these time periods. For example, most spontaneous abortions take place during the first trimester, whereas most women with hypertensive disorders due to pregnancy are diagnosed during the third trimester.
In modern obstetrics, the clinical use of trimesters to describe a specific pregnancy is imprecise. For example, it is inappropriate in cases of uterine hemorrhage to categorize the problem temporally as “third-trimester bleeding.” Appropriate management for the mother and her fetus will vary remarkably depending on whether bleeding begins early or late in the third trimester (Chap. 41, p. 782). Because precise knowledge of fetal age is imperative for ideal obstetrical management, the clinically appropriate unit is weeks of gestation completed. And more recently, clinicians designate gestational age using completed weeks and days, for example, 334/7 weeks or 33 + 4, for 33 completed weeks and 4 days.
Previous and Current Health Status
For the most part, the same essentials go into appropriate history taking from the pregnant woman as elsewhere in medicine. In addition to queries concerning medical or surgical disorders, detailed information regarding previous pregnancies is essential as many obstetrical complications tend to recur in subsequent pregnancies.
The menstrual history is also important. The woman who spontaneously menstruates approximately every 28 days is most likely to ovulate at midcycle. Thus, gestational or menstrual age is the number of weeks since the onset of the last menstrual period. If her menstrual cycles were significantly longer than 28 to 30 days, ovulation more likely occurred well beyond 14 days. If the intervals were much longer and irregular, chronic anovulation is likely to have preceded some of the episodes identified as menses. Thus, without a history of regular, predictable, cyclic, spontaneous menses that suggest ovulatory cycles, accurate dating of pregnancy by history and physical examination is difficult.
It is also important to ascertain whether or not steroidal contraceptives were used before the pregnancy. Because ovulation may not have resumed 2 weeks after the onset of the last withdrawal bleeding and instead may have occurred at an appreciably later and highly variable date, using the time of ovulation for predicting the time of conception in this circumstance may be erroneous. Use of sonography in early pregnancy will clarify gestational age in these situations.
The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) define psychosocial issues as nonbiomedical factors that affect mental and physical well-being. Women should be screened regardless of social status, education level, race, or ethnicity. Such screening should seek barriers to care, communication obstacles, nutritional status, unstable housing, desire for pregnancy, safety concerns that include intimate partner violence, depression, stress, and use of substances such as tobacco, alcohol, and illicit drugs. This screening should be performed on a regular basis, at least once per trimester, to identify important issues and reduce adverse pregnancy outcomes. Coker and colleagues (2012) compared pregnancy outcomes in women before and after implementation of a universal psychosocial screening program and found that screened women were less likely to have preterm or low-birthweight newborns. Although this study was observational, these investigators also reported decreased rates of gestational diabetes, premature rupture of membranes, and vaginal bleeding in women who underwent universal screening.
There are unequivocal adverse perinatal sequelae for smoking (United States Department of Health and Human Services, 2000). Such data have been included on the birth certificate since 1989. The number of pregnant women who smoke continues to decline. From 2000 to 2010, the prevalences were 12 to 13 percent (Tong, 2013). Based on the Pregnancy Risk Assessment Monitoring System (PRAMS), 13 percent of women admitted to smoking. These women were more likely younger, had less education, and were either Alaska Natives or American Indians (Centers for Disease Control and Prevention, 2012b).
Numerous adverse outcomes have been linked to smoking during pregnancy. Potential teratogenic effects are reviewed in Chapter 12 (p. 255). There is a twofold risk of placenta previa, placental abruption, and premature membrane rupture compared with nonsmokers. Further, neonates born to women who smoke are more likely to be preterm, have lower birth-weights, and are more likely to die of sudden infant death syndrome (SIDS) than infants born to nonsmokers (Tong, 2009). In 2005, the incidence of low-birthweight infants born to American women who smoked during pregnancy was 11.9 percent compared with 7.5 percent born to nonsmokers (Martin, 2007). Risks for spontaneous abortion, fetal death, and fetal digital anomalies are also increased (Man, 2006). Finally, children who were exposed to smoking in utero are at increased risk for asthma, infantile colic, and childhood obesity (American College of Obstetricians and Gynecologists, 2013i).
Several pathophysiological mechanisms have been proposed to explain these adverse outcomes. They include fetal hypoxia from increased carboxyhemoglobin, reduced uteroplacental blood flow, and direct toxic effects of nicotine and other compounds in smoke (Jazayeri, 1998). Nicotine transfer is so efficient that fetal nicotine exposure is greater than that of the mother (Luck, 1985). Exposed fetuses have decreased heart rate variability due to impaired autonomic regulation (Zeskind, 2006).
Smoking Cessation. The United States Department of Health and Human Services recommends that clinicians offer counseling and effective intervention options to pregnant smokers at the first and subsequent prenatal visits. Although benefits are greatest if smoking ceases early in pregnancy or preferably preconceptionally, quitting at any stage of pregnancy can improve perinatal outcomes (England, 2001; Fiore, 2008).
Person-to-person psychosocial interventions are significantly more successful in achieving smoking abstinence in pregnancy than are simple advisements to quit (Fiore, 2008). One example is a brief counseling session covering the “5As” of smoking cessation (Table 9-3). This approach to counseling can be accomplished in 15 minutes or less and has been proven to be effective when initiated by health-care providers (American College of Obstetricians and Gynecologists, 2013i).
TABLE 9-3. Five A’s of Smoking Cessation
ASK about smoking at the first and subsequent prenatal visits. To improve assessment accuracy, a patient should choose the following statement that best describes her smoking status:
I smoke regularly now; the same as before pregnancy.
I smoke regularly now, but I’ve cut down with pregnancy. I smoke every once in a while.
I have quit smoking since pregnancy.
I wasn’t smoking before pregnancy, and I do not currently smoke.
If smoking abstinence has already begun, then reinforce her decision to quit, congratulate her on success, and encourage her continued abstinence. For persistent smokers, proceed to the following steps:
ADVISE with clear, strong statements that explain the risks of continued smoking to the woman, fetus, and newborn.
ASSESS the patient’s willingness to attempt cessation.
ASSIST with pregnancy-specific, self-help smoking cessation materials. Offer a direct referral to the smoker’s quit line (1–800-QUIT NOW) to provide ongoing counseling and support.
ARRANGE to track smoking abstinence progress at subsequent visits.
Adapted from Fiore, 2008.
Nicotine replacement products have not been sufficiently evaluated to determine their effectiveness and safety in pregnancy. Trials evaluating such therapy have yielded conflicting evidence. Wisborg and colleagues (2000) randomly assigned 250 women who smoked at least 10 cigarettes per day to receive a nicotine or placebo patch beginning after the first trimester. There were no significant differences in birthweights or in smoking cessation or preterm delivery rates between the two groups. Pollak and associates (2007) randomized 181 pregnant smokers to cognitive-behavioral therapy alone versus this therapy plus nicotine replacement. They identified significantly improved smoking cessation rates in the women with nicotine replacement at 7 weeks after randomization and at 38 weeks’ gestation. The trial was terminated early due to an increased rate of negative birth outcomes in the nicotine replacement arm. Some of these included neonatal intensive care unit admission, small-for-gestational age, and placental abruption. Because of limited available evidence to support pharmacotherapy for smoking cessation in pregnancy, the American College of Obstetricians and Gynecologists (2013i) has recommended that if nicotine replacement therapy is used, it should be done with close supervision and after careful consideration of the risks of smoking versus nicotine replacement.
Ethyl alcohol or ethanol is a potent teratogen that causes a fetal syndrome characterized by growth restriction, facial abnormalities, and central nervous system dysfunction (Chap. 12, p. 245). Women who are pregnant or considering pregnancy should abstain from using any alcoholic beverages. The Centers for Disease Control and Prevention (2012a) analyzed data from the Behavioral Risk Factor Surveillance System from 2006 to 2010 and estimated that 7.6 percent of pregnant women used alcohol and 1.4 percent reported binge drinking. By comparison, in 1999, rates of alcohol use and binge drinking were estimated to be 12.8 and 2.7 percent, respectively (Centers for Disease Control and Prevention, 2002). Among pregnant women, those most likely to use alcohol were aged 35 to 44 years, white, college graduates, or employed. The American College of Obstetricians and Gynecologists (2008), in their committee opinion on this topic, has reviewed methods for screening women during pregnancy for alcohol abuse and for illicit drug use.
It is estimated that 10 percent of fetuses are exposed to one or more illicit drugs (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). Agents may include heroin and other opiates, cocaine, amphetamines, barbiturates, and marijuana. Chronic use of large quantities is harmful to the fetus (Chap. 12, p. 253). Well-documented sequelae include fetal-growth restriction, low birthweight, and drug withdrawal soon after birth. Women who use such drugs frequently do not seek prenatal care, or if they do, they may not admit to substance abuse. El-Mohandes and associates (2003) reported that when women who use illicit drugs receive prenatal care, the risks for preterm birth and low birthweight are reduced.
For women who abuse heroin, methadone maintenance can be initiated within a registered methadone treatment program to reduce complications of illicit opioid use and narcotic withdrawal, to encourage prenatal care, and to avoid drug culture risks (American College of Obstetricians and Gynecologists, 2012c). Available programs can be found through the treatment locator of the Substance Abuse and Mental Health Services Administration at www.samhsa.gov. Methadone dosages usually are initiated at 10 to 30 mg daily and titrated as needed. Although less commonly used, buprenorphine alone or in combination with naloxone may also be offered and managed by physicians with specific credentialing.
Intimate Partner Violence
This term refers to a pattern of assaultive and coercive behaviors that may include physical injury, psychological abuse, sexual assault, progressive isolation, stalking, deprivation, intimidation, and reproductive coercion (American College of Obstetricians and Gynecologists, 2012a). Such violence has been recognized as a major public health problem. Unfortunately, most abused women continue to be victimized during pregnancy. With the possible exception of preeclampsia, domestic violence is more prevalent than any major medical condition detectable through routine prenatal screening (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). The prevalence during pregnancy is estimated to be between 4 and 8 percent. As discussed in Chapter 47 (p. 951), intimate partner violence is associated with an increased risk of several adverse perinatal outcomes including preterm delivery, fetal-growth restriction, and perinatal death.
The American College of Obstetricians and Gynecologists (2012a) has provided methods for domestic violence screening and recommends their use at the first prenatal visit, then again at least once per trimester, and again at the postpartum visit. Such screening should be done privately and away from family members and friends. Patient self-administered or computerized screenings appear to be as effective for disclosure as clinician-directed interviews (Ahmad, 2009; Chen, 2007). Physicians should be familiar with state laws that may require reporting of intimate partner violence. Coordination with social services can be invaluable in such cases. The National Domestic Violence Hotline (1–800–799-SAFE ) is a nonprofit telephone referral service that provides individualized information regarding city-specific women’s shelter locations, counseling resources, and legal advocacy.
A thorough, general physical examination should be completed at the initial prenatal encounter. Many of the expected changes that result from normal pregnancy are addressed throughout Chapter 4 (p. 46).
Pelvic examination is performed as part of the evaluation. The cervix is visualized employing a speculum lubricated with warm water or water-based lubricant gel. Bluish-red passive hyperemia of the cervix is characteristic, but not of itself diagnostic, of pregnancy. Dilated, occluded cervical glands bulging beneath the ectocervical mucosa—nabothian cysts—may be prominent. The cervix is not normally dilated except at the external os. To identify cytological abnormalities, a Pap smear is performed according to current guidelines noted in Chapter 63 (p. 1221). Specimens for identification of Chlamydia trachomatisand Neisseria gonorrhoeae are also obtained when indicated (p. 175).
Bimanual examination is completed by palpation, with special attention given to the consistency, length, and dilatation of the cervix; to uterine and adnexal size; to the bony pelvic architecture; and to any vaginal or perineal anomalies. Later in pregnancy, fetal presentation often can also be determined. Lesions of the cervix, vagina, or vulva should be further evaluated as needed by colposcopy, biopsy, culture, or dark-field examination. The perianal region should be visualized, and digital rectal examination performed as required for complaints of rectal pain, bleeding, or mass.
Gestational Age Assessment
Precise knowledge of gestational age is one of the most important aspects of prenatal care because several pregnancy complications may develop for which optimal treatment will depend on fetal age. Gestational age can be estimated with considerable precision by appropriately timed and carefully performed clinical uterine size examination that is coupled with knowledge of the last menses. Uterine size similar to a small orange roughly correlates with a 6-week gestation; a large orange, with an 8-week pregnancy; and a grapefruit, with one at 12 weeks (Margulies, 2001). That said, a first-trimester crown-rump length is the most accurate tool for gestational age assignment and is performed as clinically indicated. As described in Chapter 10 (p. 198), later sonographic interrogation can also provide an estimated gestational age, but with declining accuracy.
Recommended routine tests at the first prenatal encounter are listed in Table 9-2. Initial blood tests include a complete blood count, a determination of blood type with Rh status, and an antibody screen. The Institute of Medicine recommends universal human immunodeficiency virus (HIV) testing, with patient notification and right of refusal, as a routine part of prenatal care. The Centers for Disease Control and Prevention (2006) as well as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) continue to support this practice. If a woman declines testing, this should be recorded in the prenatal record. All pregnant women should also be screened for hepatitis B virus, syphilis, and immunity to rubella at the initial visit. Based on their prospective investigation of 1000 women, Murray and coworkers (2002) concluded that in the absence of hypertension, routine urinalysis beyond the first prenatal visit was not necessary. A urine culture is performed because treating asymptomatic bacteruria significantly reduces the likelihood of developing symptomatic urinary tract infections in pregnancy (Chap. 53, p. 1053).
Chlamydia trachomatis is isolated from the cervix in 2 to 13 percent of pregnant women. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) recommend that all women be screened for chlamydia during the first prenatal visit, with additional third-trimester testing for those at increased risk. Risk factors include unmarried status, recent change in sexual partner or multiple concurrent partners, age younger than 25 years, inner-city residence, history or presence of other sexually transmitted diseases, and little or no prenatal care. Following treatment, a second testing—a so-called test of cure—is recommended in pregnancy 3 to 4 weeks after treatment completion (Chap. 65, p. 1270).
Neisseria gonorrhoeae is the gram-negative diplococcal bacteria responsible for causing gonorrhea. Risk factors for gonorrhea are similar for those for chlamydial infection. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) recommend that pregnant women with risk factors or those living in an area of high N gonorrhoeae prevalence be screened at the initial prenatal visit and again in the third trimester. Treatment is given for gonorrhea as well as possible coexisting chlamydial infection, as outlined in Chapter 65 (p. 1269). Test of cure is also recommended following treatment.
Pregnancy Risk Assessment
Many factors exist that can adversely affect maternal and/or fetal well-being. Some are evident at conception, but many become apparent during the course of pregnancy. The designation of “high-risk pregnancy” is overly vague for an individual patient and probably should be avoided if a more specific diagnosis has been assigned. Some common risk factors for which consultation is recommended by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) are shown in Table 9-4. Some conditions may require the involvement of a maternal-fetal medicine subspecialist, geneticist, pediatrician, anesthesiologist, or other medical specialist in the evaluation, counseling, and care of the woman and her fetus.
TABLE 9-4. Conditions for Which Maternal-Fetal Medicine Consultation May Be Beneficial
Medical History and Conditions
Cardiac disease—including cyanotic, prior myocardial infarction, moderate to severe valvular stenosis or regurgitation, Marfan syndrome, prosthetic valve, American Heart Association class II or greater
Diabetes mellitus with evidence of end-organ damage or uncontrolled hyperglycemia
Family or personal history of genetic abnormalities
Chronic hypertension if uncontrolled or associated with renal or cardiac disease
Renal insufficiency if associated with significant proteinuria (≥ 500 mg/24 hour), serum creatinine ≥ 1.5 mg/dL, or hypertension
Pulmonary disease if severe restrictive or obstructive, including severe asthma
Human immunodeficiency virus infection
Prior pulmonary embolus or deep-vein thrombosis
Severe systemic disease, including autoimmune conditions
Epilepsy if poorly controlled or requires more than one anticonvulsant
Cancer, especially if treatment is indicated in pregnancy
Obstetrical History and Conditions
CDE (Rh) or other blood group alloimmunization (excluding ABO, Lewis)
Prior or current fetal structural or chromosomal abnormality
Desire or need for prenatal diagnosis or fetal therapy
Periconceptional exposure to known teratogens
Infection with or exposure to organisms that cause congenital infection
Higher-order multifetal gestation
Severe disorders of amnionic fluid volume
SUBSEQUENT PRENATAL VISITS
Subsequent prenatal visits have been traditionally scheduled at 4-week intervals until 28 weeks, then every 2 weeks until 36 weeks, and weekly thereafter. Women with complicated pregnancies often require return visits at 1- to 2-week intervals. For example, in twin pregnancies, Luke and colleagues (2003) found that a specialized prenatal care program emphasizing nutrition and education and requiring return visits every 2 weeks resulted in improved outcomes.
In 1986, the Department of Health and Human Services convened an expert panel to review the content of prenatal care. This report was subsequently reevaluated and revised in 2005 (Gregory, 2006). The panel recommended, among other things, early and continuing risk assessment that is patient specific. It also endorsed flexibility in clinical visit spacing; health promotion and education, including preconceptional care; medical and psychosocial interventions; standardized documentation; and expanded prenatal care objectives—to include family health up to 1 year after birth.
The World Health Organization (WHO) conducted a multicenter randomized trial with almost 25,000 women comparing routine prenatal care with an experimental model designed to minimize visits (Villar, 2001). In the new model, women were seen once in the first trimester and screened for certain risks. Those without anticipated complications—80 percent of those screened—were seen again at 26, 32, and 38 weeks. Compared with routine prenatal care, which required a median of eight visits, the new model required a median of only five. No disadvantages were attributed to the regimen with fewer visits, and these findings were consistent with other randomized trials (Clement, 1999; McDuffie, 1996).
At each return visit, the well-being of mother and fetus are assessed (see Table 9-2). Fetal heart rate, growth, amnionic fluid volume, and activity are evaluated. Maternal blood pressure and weight and their extent of change are assessed. Symptoms such as headache, altered vision, abdominal pain, nausea and vomiting, bleeding, vaginal fluid leakage, and dysuria are sought. Uterine examination measures size from the symphysis to the fundus. In late pregnancy, vaginal examination often provides valuable information that includes confirmation of the presenting part and its station, clinical estimation of pelvic capacity and its general configuration, amnionic fluid volume adequacy, and cervical consistency, effacement, and dilatation (Chap. 22, p. 438).
Between 20 and 34 weeks, the height of the uterine fundus measured in centimeters correlates closely with gestational age in weeks (Calvert, 1982; Jimenez, 1983; Quaranta, 1981). This measurement is used to monitor fetal growth and amnionic fluid volume. It is measured as the distance along the abdominal wall from the top of the symphysis pubis to the top of the fundus. Importantly, the bladder must be emptied before fundal measurement. Worthen and Bustillo (1980) demonstrated that at 17 to 20 weeks, fundal height was 3 cm higher with a full bladder. Obesity or the presence of uterine masses such as leiomyomata may also limit fundal height accuracy. In such cases, sonography may be necessary for assessment. Moreover, using fundal height alone, fetal-growth restriction may be undiagnosed in up to a third of cases (American College of Obstetricians and Gynecologists, 2013b).
Fetal Heart Sounds
Instruments incorporating Doppler ultrasound are often used to easily detect fetal heart action, and in the absence of maternal obesity, heart sounds are almost always detectable by 10 weeks with such instruments (Chap. 24, p. 474). The fetal heart rate ranges from 110 to 160 beats per minute and is typically heard as a double sound.
Using a standard nonamplified stethoscope, the fetal heart may be audible as early as 16 weeks in some women. Herbert and coworkers (1987) reported that the fetal heart was audible by 20 weeks in 80 percent of women, and by 22 weeks, heart sounds were heard in all. Because the fetus moves freely in amnionic fluid, the site on the maternal abdomen where fetal heart sounds can be heard best will vary.
As described in detail in Chapter 10 (p. 199), sonography provides invaluable information regarding fetal anatomy, growth, and well-being, and most women in the United States have at least one prenatal sonographic examination during pregnancy (American College of Obstetricians and Gynecologists, 2011b). Recent trends suggest that the number of these examinations performed per pregnancy is increasing. Siddique and associates (2009) reported that the average number of sonographic evaluations per pregnancy increased from 1.5 in 1995 through 1997 to 2.7 almost 10 years later. This trend was noted in both high- and low-risk pregnancies. The actual clinical utility of increasing sonography use in pregnancy has not been demonstrated, and it is unclear that the cost-benefit ratio is justified (Washington State Health Care Authority, 2010). The American College of Obstetricians and Gynecologists (2011b) has concluded that sonography should be performed only when there is a valid medical indication under the lowest possible ultrasound exposure setting. The College further indicates that a physician is not obligated to perform sonography without a specific indication in a low-risk patient, but that if she requests sonographic screening, it is reasonable to honor her request.
Subsequent Laboratory Tests
If initial results were normal, most tests need not be repeated. Fetal aneuploidy screening may be performed at 11 to 14 weeks and/or at 15 to 20 weeks, depending on the protocol selected as described in Chapter 14. Serum screening for neural-tube defects is offered at 15 to 20 weeks (Chap. 14, p. 284). Hematocrit or hemoglobin determination, along with syphilis serology if it is prevalent in the population, should be repeated at 28 to 32 weeks (Hollier, 2003; Kiss, 2004). For women at increased risk for HIV acquisition during pregnancy, repeat testing is recommended in the third trimester, preferably before 36 weeks’ gestation (American College of Obstetricians and Gynecologists, 2011a). Similarly, women who engage in behaviors that place them at high risk for hepatitis B infection should be retested at the time of hospitalization for delivery (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). Women who are D (Rh) negative and are unsensitized should have an antibody screening test repeated at 28 to 29 weeks, with administration of anti-D immune globulin if they remain unsensitized (Chap. 15, p. 311).
Group B Streptococcal Infection
The Centers for Disease Control and Prevention (2010b) recommend that vaginal and rectal group B streptococcal (GBS) cultures be obtained in all women between 35 and 37 weeks’ gestation, and the American College of Obstetricians and Gynecologists (2013g) has endorsed this recommendation. Intrapartum antimicrobial prophylaxis is given for those whose cultures are positive. Women with GBS bacteriuria or a previous infant with invasive disease are given empirical intrapartum prophylaxis. These infections are discussed in detail in Chapter 64 (p. 1249).
All pregnant women should be screened for gestational diabetes mellitus, whether by history, clinical factors, or routine laboratory testing. Although laboratory testing between 24 and 28 weeks’ gestation is the most sensitive approach, there may be pregnant women at low risk who are less likely to benefit from testing (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). Gestational diabetes is discussed in Chapter 57 (p. 1136).
Selected Genetic Screening
Selected screening for certain genetic abnormalities should be offered to those at increased risk based on family history, ethnic or racial background, or age (American College of Obstetricians and Gynecologists, 2009c, 2011c, 2013h). These are discussed in greater detail in Chapters 13 (p. 275) and 14 (p. 294). Some examples include testing for Tay-Sachs disease for persons of Eastern European Jewish or French Canadian ancestry; β-thalassemia for those of Mediterranean, Southeast Asian, Indian, Pakistani, or African ancestry; α-thalassemia for individuals of Southeast Asian or African ancestry; sickle-cell anemia for people of African, Mediterranean, Middle Eastern, Caribbean, Latin American, or Indian descent; and trisomy 21 for those with advanced maternal age.
Weight Gain Recommendations
For the first half of the 20th century, it was recommended that weight gain during pregnancy be limited to less than 20 lb or about 9 kg. It was believed that such restriction would prevent gestational hypertension and fetal macrosomia. By the 1970s, however, women were encouraged to gain at least 25 lb or 11 to 12 kg to prevent preterm birth and fetal-growth restriction, a recommendation supported by subsequent research (Ehrenberg, 2003). The Institute of Medicine and National Research Council (2009) revised its guidelines for weight gain in pregnancy and continues to stratify suggested weight gain ranges based on prepregnancy body mass index (BMI) (Table 9-5). BMI can easily be calculated with commonly available graphs (Fig. 48-1, p. 962). Of note, the new guidelines include a specific, relatively narrow range of recommended weight gains for obese women. Also, the same recommendations apply to adolescents, short women, and women of all racial and ethnic groups. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) have endorsed these guidelines.
TABLE 9-5. Recommendations for Total and Rate of Weight Gain During Pregnancy, by Prepregnancy BMIa
As emphasized by Catalano (2007), when the Institute of Medicine guidelines were formulated, concern focused on low-birthweight newborns. Current emphasis now, however, is on the obesity epidemic. This likely explains renewed interest in lower weight gains during pregnancy. As discussed in Chapter 48 (p. 965), obesity is associated with significantly increased risks for gestational hypertension, preeclampsia, gestational diabetes, macrosomia, cesarean delivery, and other complications. The risk appears “dose related” to prenatal weight gain. In a population-based cohort of more than 120,000 obese pregnant women, Kiel and associates (2007) found that those who gained less than 15 pounds had the lowest rates of preeclampsia, large-for-gestational age neonates, and cesarean delivery. Among 100,000 women with normal prepregnancy BMI, DeVader and colleagues (2007) found that those who gained less than 25 pounds during pregnancy had a lower risk for preeclampsia, failed induction, cephalopelvic disproportion, cesarean delivery, and large-for-gestational age infants. This cohort, however, had an increased risk for small-for-gestational age newborns.
There is irrefutable evidence that maternal weight gain during pregnancy influences birthweight. Martin and coworkers (2009) studied this using birth certificate data for 2006. As shown in Figure 9-4, 60 percent of pregnant women gained 26 lb or more. Maternal weight gain had a positive correlation with birthweight. Moreover, women with the greatest risk—14 percent—for delivering an infant weighing < 2500 g were those with weight gain < 16 lb. Nearly 20 percent of births to women with such low weight gains were preterm.
FIGURE 9-4 Percentage distribution of maternal weight gain in the United States reported on 2006 birth certificates. (From Martin, 2009.)
Meaningful studies of nutrition in human pregnancy are exceedingly difficult to design because experimental dietary deficiency is not ethical. In those instances in which severe nutritional deficiencies have been induced as a consequence of social, economic, or political disaster, coincidental events have often created many variables, the effects of which are not amenable to quantification. Some past experiences suggest, however, that in otherwise healthy women, a state of near starvation is required to establish clear differences in pregnancy outcome.
During the severe European winter of 1944 to 1945, nutritional deprivation of known intensity prevailed in a well-circumscribed area of The Netherlands occupied by the German military (Kyle, 2006). At the lowest point during this Dutch Hunger Winter, rations reached 450 kcal/day, with generalized rather than selective malnutrition. Smith (1947) analyzed the outcomes of pregnancies that were in progress during this 6-month famine. Median infant birthweights decreased approximately 250 g and rose again after food became available. This indicated that birthweight can be influenced significantly by starvation during later pregnancy. The perinatal mortality rate, however, was not altered, nor was the incidence of malformations significantly increased. Interestingly, the frequency of pregnancy “toxemia” declined.
Evidence of impaired brain development has been obtained in some animal fetuses whose mothers had been subjected to intense dietary deprivation. Subsequent intellectual development was studied by Stein and associates (1972) in young male adults whose mothers had been starved during pregnancy in the Hunger Winter. The comprehensive study was made possible because all males at age 19 underwent compulsory examination for military service. It was concluded that severe dietary deprivation during pregnancy caused no detectable effects on subsequent mental performance.
Several studies of the long-term consequences to this cohort of children born to nutritionally deprived women have been performed and have been reviewed by Kyle and Pichard (2006). Progeny deprived in mid to late pregnancy were lighter, shorter, and thinner at birth, and they had a higher incidence of subsequent diminished glucose tolerance, hypertension, reactive airway disease, dyslipidemia, and coronary artery disease. Early pregnancy deprivation was associated with increased obesity in adult women but not men. Early starvation was also linked to increased central nervous system anomalies, schizophrenia, and schizophrenia-spectrum personality disorders.
These observations, as well as others, have led to the concept of fetal programming by which adult morbidity and mortality are related to fetal health. Known widely as the Barker hypothesis, as promulgated by Barker and colleagues (1989), this concept is discussed in Chapter 44 (p. 876).
Weight Retention after Pregnancy
Not all the weight gained during pregnancy is lost during and immediately after delivery (Hytten, 1991). Schauberger and coworkers (1992) studied prenatal and postpartum weights in 795 women. Their average weight gain was 28.6 lb or 4.8 kg. As shown in Figure 9-5, most maternal weight loss was at delivery—approximately 12 lb or 5.5 kg—and in the ensuing 2 weeks—approximately 9 lb or 4 kg. An additional 5.5 lb or 2.5 kg was lost between 2 weeks and 6 months postpartum. Thus, average total weight loss resulted in an average retained pregnancy weight of 3 lb or 1.4 kg. Overall, the more weight that was gained during pregnancy, the more that was lost postpartum. Interestingly, there is no relationship between prepregnancy BMI or prenatal weight gain and weight retention (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). Accruing weight with age—rather than parity—is considered the main factor affecting weight gain over time.
FIGURE 9-5 Cumulative weight loss from last antepartum visit to 6 months postpartum. *Significantly different from 2-week weight loss; **Significantly different from 6-week weight loss. (Redrawn from Schauberger, 1992, with permission.)
Recommended Dietary Allowances
Periodically, the Institute of Medicine (2006, 2011) publishes recommended dietary allowances, including those for pregnant or lactating women. The latest recommendations are summarized in Table 9-6. Certain prenatal vitamin–mineral supplements may lead to intakes well in excess of the recommended allowances. Moreover, the use of excessive supplements, which often are self-prescribed, has led to concern regarding nutrient toxicities during pregnancy. Those with potentially toxic effects include iron, zinc, selenium, and vitamins A, B6, C, and D. In particular, excessive vitamin A—more than 10,000 IU per day—may be teratogenic (Chap. 12, p. 252). Vitamin and mineral intake more than twice the recommended daily dietary allowance shown in Table 9-6 should be avoided.
TABLE 9-6. Recommended Daily Dietary Allowances for Adolescent and Adult Pregnant and Lactating Women
As shown in Figure 9-6, pregnancy requires an additional 80,000 kcal, mostly during the last 20 weeks. To meet this demand, a caloric increase of 100 to 300 kcal per day is recommended during pregnancy (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). This intake increase, however, should not be divided equally during the course of pregnancy. The Institute of Medicine (2006) recommends adding 0, 340, and 452 kcal/day to the estimated nonpregnant energy requirements in the first, second, and third trimesters, respectively. Calories are necessary for energy. Whenever caloric intake is inadequate, protein is metabolized rather than being spared for its vital role in fetal growth and development. Total physiological requirements during pregnancy are not necessarily the sum of ordinary nonpregnant requirements plus those specific to pregnancy. For example, the additional energy required during pregnancy may be compensated in whole or in part by reduced physical activity (Hytten, 1991).
FIGURE 9-6 Cumulative kilocalories required for pregnancy. (Redrawn from Chamberlain, 1998, with permission.)
To the basic protein needs of the nonpregnant woman are added the demands for growth and remodeling of the fetus, placenta, uterus, and breasts, as well as increased maternal blood volume (Chap. 4, p. 53). During the second half of pregnancy, approximately 1000 g of protein are deposited, amounting to 5 to 6 g/day (Hytten, 1971). Most amino-acid levels in maternal plasma fall markedly, including ornithine, glycine, taurine, and proline (Hytten, 1991). Exceptions during pregnancy are glutamic acid and alanine, the concentrations of which rise.
Preferably, most protein should be supplied from animal sources, such as meat, milk, eggs, cheese, poultry, and fish. These furnish amino acids in optimal combinations. Milk and dairy products have long been considered nearly ideal sources of nutrients, especially protein and calcium, for pregnant or lactating women. Ingestion of specific fish and potential methylmercury toxicity are discussed on page 183.
The intakes recommended by the Institute of Medicine (2006) for various minerals are presented in Table 9-6. With the exception of iron and iodine, practically all diets that supply sufficient calories for appropriate weight gain will contain enough minerals to prevent deficiency.
The reasons for substantively increased iron requirements during pregnancy are discussed in Chapter 4 (p. 55). Of the approximately 300 mg of iron transferred to the fetus and placenta and the 500 mg incorporated into the expanding maternal hemoglobin mass, nearly all is used after midpregnancy. During that time, iron requirements imposed by pregnancy and maternal excretion total approximately 7 mg per day (Pritchard, 1970). Few women have sufficient iron stores or dietary iron intake to supply this amount. Thus, the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) endorse the recommendation by the National Academy of Sciences that at least 27 mg of elemental iron supplement be given daily to pregnant women. This amount is contained in most prenatal vitamins.
Scott and coworkers (1970) established that as little as 30 mg of elemental iron, supplied as ferrous gluconate, sulfate, or fumarate and taken daily throughout the latter half of pregnancy, provides sufficient iron to meet pregnancy requirements and to protect preexisting iron stores. This amount will also provide for iron requirements of lactation. The pregnant woman may benefit from 60 to 100 mg of elemental iron per day if she is large, has twin fetuses, begins supplementation late in pregnancy, takes iron irregularly, or has a somewhat depressed hemoglobin level. The woman who is overtly anemic from iron deficiency responds well to oral supplementation with iron salts (Chap. 56, p. 1102).
Because iron requirements are slight during the first 4 months of pregnancy, it is not necessary to provide supplemental iron during this time. Withholding iron supplementation during the first trimester of pregnancy also avoids the risk of aggravating nausea and vomiting (Gill, 2009). Ingestion of iron at bedtime or on an empty stomach aids absorption and appears to minimize the possibility of an adverse gastrointestinal reaction.
Since 1997, the Food and Drug Administration (FDA) has required that iron preparations containing 30 mg or more of elemental iron per tablet be packaged as individual doses, such as in blister packages. This regulation is targeted at preventing accidental iron poisoning in children.
The recommended daily iodine allowance is 220 μg (Table 9-6). The use of iodized salt and bread products is recommended during pregnancy to offset the increased fetal requirements and maternal renal losses of iodine. Despite this, iodine intake has declined substantially in the last 15 years, and in some areas, it is probably inadequate (Chap. 58, p. 1155). Interest in increasing dietary iodine was heightened by reports linking subclinical maternal hypothyroidism to adverse pregnancy outcomes and possible neurodevelopmental defects in children (Casey, 2005; Haddow, 1999). Severe maternal iodine deficiency predisposes offspring to endemic cretinism, characterized by multiple severe neurological defects. In parts of China and Africa where this condition is common, iodide supplementation very early in pregnancy prevents some cretinism cases (Cao, 1994). To obviate this, many prenatal supplements now contain various quantities of iodine.
As discussed in Chapter 4 (p. 54), the pregnant woman retains approximately 30 g of calcium. Most of this is deposited in the fetus late in pregnancy (Pitkin, 1985). This amount of calcium represents only approximately 2.5 percent of total maternal calcium, most of which is in bone and can readily be mobilized for fetal growth. Moreover, Heaney and Skillman (1971) demonstrated increased calcium absorption by the intestine and progressive retention throughout pregnancy. Efforts to prevent preeclampsia using routine calcium supplementation have not proven efficacious (Chap. 40, p. 748).
Severe zinc deficiency in a given person may lead to poor appetite, suboptimal growth, and impaired wound healing. During pregnancy, the recommended daily intake is approximately 12 mg. But, the safe level of zinc supplementation for pregnant women has not been clearly established. Goldenberg and colleagues (1995) randomly assigned 580 indigent women to daily 25-mg zinc supplementation or placebo beginning at midpregnancy. Plasma zinc levels were significantly higher in women who received supplements. Infants born to zinc-supplemented women were slightly larger—mean increase 125 g—and had a slightly larger head circumference—mean 4 mm. Later, Osendarp and associates (2001) randomly assigned 420 women in Bangladesh to receive either daily 30-mg zinc supplementation or placebo from 12 to 16 weeks’ gestation until delivery. Supplementation did not improve birthweight. However, low-birthweight infants of mothers who received zinc had reduced risks of acute diarrhea, dysentery, and impetigo. In a follow-up study of these infants at 13 months, zinc supplementation did not benefit their developmental outcome (Hamadani, 2002).
Deficiency of this mineral as a consequence of pregnancy has not been recognized. Undoubtedly, during prolonged illness with no magnesium intake, the plasma level might become critically low, as it would in the absence of pregnancy. We have observed magnesium deficiency during pregnancies in some with previous intestinal bypass surgery. Sibai and coworkers (1989) randomly assigned 400 normotensive primigravid women to 365-mg elemental magnesium supplementation or placebo tablets from 13 to 24 weeks’ gestation. Supplementation did not improve any measures of pregnancy outcome.
Copper, selenium, chromium, and manganese all have important roles in certain enzyme functions. In general, most are provided by an average diet. A severe geochemical selenium deficiency has been identified in a large area of China. Deficiency is manifested by a frequently fatal cardiomyopathy in young children and reproductive-aged women. Conversely, selenium toxicity resulting from oversupplementation also has been observed. There is no reported need to supplement selenium in American women.
The concentration of potassium in maternal plasma decreases by approximately 0.5 mEq/L by midpregnancy (Brown, 1986). Potassium deficiency develops in the same circumstances as in nonpregnant individuals.
There is no evidence that supplemental fluoride during pregnancy is beneficial (Institute of Medicine, 1990). Maheshwari and colleagues (1983) found that fluoride metabolism is not altered appreciably during pregnancy. Horowitz and Heifetz (1967) concluded that there were no additional benefits from maternal ingestion of fluoridated water if the offspring ingested such water from birth. Sa Roriz Fonteles and associates (2005) studied microdrill biopsies of deciduous teeth and concluded that prenatal fluoride provided no additional fluoride uptake compared with postnatal fluoride alone. Supplemental fluoride ingested by lactating women does not increase the fluoride concentration in breast milk (Ekstrand, 1981).
The increased requirements for most vitamins during pregnancy shown in Table 9-6 usually are supplied by any general diet that provides adequate calories and protein. The exception is folic acid during times of unusual requirements, such as pregnancy complicated by protracted vomiting, hemolytic anemia, or multiple fetuses. That said, in impoverished countries, routine multivitamin supplementation reduced the incidence of low-birthweight and growth-restricted fetuses, but did not alter preterm delivery or perinatal mortality rates (Fawzi, 2007).
The Centers for Disease Control and Prevention (2004) estimated that the number of pregnancies affected by neural-tube defects has decreased from 4000 pregnancies per year to approximately 3000 per year since mandatory fortification of cereal products with folic acid in 1998. Perhaps more than half of all neural-tube defects can be prevented with daily intake of 400 μg of folic acid throughout the periconceptional period. Putting 140 μg of folic acid into each 100 g of grain products may increase the folic acid intake of the average American woman of childbearing age by 100 μg per day. Because nutritional sources alone are insufficient, however, folic acid supplementation is still recommended (American College of Obstetricians and Gynecologists, 2013f). Likewise, the United States Preventive Services Task Force (2009) has issued a Level-A recommendation that all women planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg of folic acid. Using data from 15 international registries, Botto and associates (2006) demonstrated a significant reduction in neural-tube defect rates only in countries with folic acid fortification programs. There was no rate decrease in areas with supplementation recommendations alone.
A woman with a prior child with a neural-tube defect can reduce the 2- to 5-percent recurrence risk by more than 70 percent with daily 4-mg folic acid supplements the month before conception and during the first trimester. As emphasized by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012), this dose should be consumed as a separate supplement and not as multivitamin tablets. This practice avoids excessive intake of fat-soluble vitamins. Unfortunately, surveys continue to suggest that many women, especially among minorities, remain unaware of the recommendations regarding folic acid supplementation (Perlow, 2001; Rinsky-Eng, 2002). This important relationship between folic acid deficiency and neural-tube defects is further discussed in Chapter 14(p. 284).
Although essential, this vitamin has been associated with congenital malformations when taken in higher doses (> 10,000 IU per day) during pregnancy. These malformations are similar to those produced by the vitamin A derivative isotretinoin—Accutane—which is one of the most potent teratogens (Chap. 12, p. 251). Beta-carotene, the precursor of vitamin A found in fruits and vegetables, has not been shown to produce vitamin A toxicity. Most prenatal vitamins contain vitamin A in doses considerably below the teratogenic threshold. Dietary intake of vitamin A in the United States appears to be adequate, and additional supplementation is not routinely recommended.
Vitamin A deficiency is an endemic nutritional problem in the developing world. It is estimated that 6 million pregnant women suffer from night blindness secondary to vitamin A deficiency (West, 2003). In a study from India, Radhika and coworkers (2002) found overt deficiency manifested as night blindness in 3 percent of 736 women in their third trimester. Another 27 percent had subclinical vitamin A deficiency defined as a serum retinol concentration below 20 μg/dL. Vitamin A deficiency, whether overt or subclinical, was associated with an increased risk of maternal anemia and spontaneous preterm birth.
Maternal plasma vitamin B12 levels decrease in normal pregnancy mostly as a result of reduced plasma levels of their carrier proteins—transcobalamins. Vitamin B12 occurs naturally only in foods of animal origin, and strict vegetarians may give birth to infants whose B12 stores are low. Likewise, because breast milk of a vegetarian mother contains little vitamin B12, the deficiency may become profound in the breast-fed infant (Higginbottom, 1978). Excessive ingestion of vitamin C also can lead to a functional deficiency of vitamin B12. Although its role is still controversial, low levels of vitamin B12preconceptionally, similar to folate, may increase the risk of neural-tube defects (Molloy, 2009; Thompson, 2009).
Limited clinical trials in pregnant women have failed to demonstrate any benefits of vitamin B6 supplements (Thaver, 2006). For women at high risk for inadequate nutrition—for example, substance abusers, adolescents, and those with multifetal gestations—a daily 2-mg supplement is recommended. As discussed on page 187 and in Chapter 54 (p. 1072), vitamin B6, when combined with the antihistamine doxylamine, is helpful in many cases of nausea and vomiting of pregnancy (Boskovic, 2003; Staroselsky, 2007).
The recommended dietary allowance for vitamin C during pregnancy is 80 to 85 mg/day—approximately 20 percent more than when nonpregnant (see Table 9-6). A reasonable diet should readily provide this amount. The maternal plasma level declines during pregnancy, whereas the cord-blood level is higher, a phenomenon observed with most water-soluble vitamins.
This is a fat-soluble vitamin that, after being metabolized to its active form, increases the efficiency of intestinal calcium absorption and promotes bone mineralization and growth. Unlike most vitamins that are obtained exclusively from dietary intake, vitamin D is also synthesized endogenously with exposure to sunlight. There is increasing recognition that vitamin D deficiency is common during pregnancy. This is especially true in high-risk groups such as women with limited sun exposure, ethnic minorities—particularly those with darker skin, and vegetarians (Bodnar, 2007). Such maternal deficiency can cause disordered skeletal homeostasis, congenital rickets, and fractures in the newborn (American College of Obstetricians and Gynecologists, 2011d). The Food and Nutrition Board of the Institute of Medicine (2011) established that an adequate intake of vitamin D during pregnancy and lactation was 15 μg per day (600 IU per day). In women suspected of having vitamin D deficiency, serum levels of 25-hydroxyvitamin D can be obtained. Even then, the optimal levels in pregnancy have not been established (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012).
Pragmatic Nutritional Surveillance
Although researchers continue to study the ideal nutritional regimen for the pregnant woman and her fetus, basic tenets for the clinician include:
1. In general, advise the pregnant woman to eat what she wants in amounts she desires and salted to taste.
2. Ensure that food is amply available for socioeconomically deprived women.
3. Monitor weight gain, with a goal of approximately 25 to 35 lb in women with a normal BMI.
4. Explore food intake by dietary recall periodically to discover the occasional nutritionally errant diet.
5. Give tablets of simple iron salts that provide at least 27 mg of elemental iron daily. Give folate supplementation before and in the early weeks of pregnancy. Provide iodine supplementation in areas of known dietary insufficiency.
6. Recheck the hematocrit or hemoglobin concentration at 28 to 32 weeks’ gestation to detect significant decreases.
More than half of the children in the United States are born to working mothers. Federal law prohibits employers from excluding women from job categories on the basis that they are or might become pregnant (Annas, 1991). The Family and Medical Leave Act requires that covered employers must grant up to 12 workweeks of unpaid leave to an employee for the birth and care of a newborn child. In the absence of complications, most women can continue to work until the onset of labor (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012).
Some types of work, however, may increase pregnancy complication risks. Mozurkewich and colleagues (2000) reviewed 29 studies that involved more than 160,000 pregnancies. With physically demanding work, women had a 20- to 60-percent increase in rates of preterm birth, fetal-growth restriction, or gestational hypertension. In a prospective study of more than 900 healthy nulliparas, Higgins and associates (2002) found that women who worked had a fivefold risk of preeclampsia. Newman and coworkers (2001) reported outcomes in 2929 women with singleton pregnancies studied by the Maternal-Fetal Medicine Units Network. Occupational fatigue—estimated by the number of hours standing, intensity of physical and mental demands, and environmental stressors—was associated with an increased risk of preterm premature membrane rupture. For women reporting the highest degrees of fatigue, the risk was 7.4 percent.
Thus, any occupation that subjects the pregnant woman to severe physical strain should be avoided. Ideally, no work or play should be continued to the extent that undue fatigue develops. Adequate periods of rest should be provided. It seems prudent to advise women with previous pregnancy complications that are at risk to recur—for example, preterm birth—to minimize physical work.
In general, pregnant women do not need to limit exercise, provided they do not become excessively fatigued or risk injury. Clapp and associates (2000) randomly assigned 46 pregnant women who did not exercise regularly to either no exercise or to weight-bearing exercise beginning at 8 weeks’ gestation. Exercise consisted of treadmill running, step aerobics, or stair stepper use for 20 minutes three to five times each week. They did this throughout pregnancy at an intensity level between 55 and 60 percent of the preconceptional maximum aerobic capacity. Both placental size and birthweight were significantly greater in the exercise group. Duncombe and coworkers (2006) reported similar findings in 148 women. In contrast, Magann and colleagues (2002) prospectively analyzed exercise behavior in 750 healthy women and found that working women who exercised had smaller infants and more dysfunctional labors, and they had more frequent upper respiratory infections.
The American College of Obstetricians and Gynecologists (2009b) advises a thorough clinical evaluation before recommending an exercise program. In the absence of contraindications listed in Table 9-7, pregnant women should be encouraged to engage in regular, moderate-intensity physical activity for 30 minutes or more day. Each activity should be reviewed individually for its potential risk. Pregnant women should refrain from activities with a high risk of falling or abdominal trauma. Similarly, scuba diving is avoided because the fetus is at increased risk for decompression sickness.
Absolute Contraindications to Aerobic Exercise During Pregnancy
• Hemodynamically significant heart disease
• Restrictive lung disease
• Incompetent cervix/cerclage
• Multiple gestation at risk for preterm labor
• Persistent second- or third-trimester bleeding
• Placenta previa after 26 weeks
• Preterm labor during the current pregnancy
• Ruptured membranes
• Preeclampsia/gestational hypertension
Relative Contraindications to Aerobic Exercise During Pregnancy
• Severe anemia
• Unevaluated maternal cardiac arrhythmia
• Chronic bronchitis
• Poorly controlled type 1 diabetes
• Extreme morbid obesity
• Extreme underweight (BMI < 12)
• History of extremely sedentary lifestyle
• Intrauterine growth restriction in current pregnancy
• Poorly controlled hypertension
• Orthopedic limitations
• Poorly controlled seizure disorder
• Poorly controlled hyperthyroidism
• Heavy smoker
From Exercise during pregnancy and the postpartum period. ACOG Committee Opinion No. 267. American College of Obstetricians and Gynecologists. Obstet Gynecol 2002;99:171–173; reaffirmed 2009b.
In the setting of certain pregnancy complications, it is wise to abstain from exercise and even limit physical activity. For example, some women with pregnancy-associated hypertensive disorders, preterm labor, placenta previa, or severe cardiac or pulmonary disease may gain from being sedentary. Also, those with multiple or suspected growth-restricted fetuses may be served by greater rest.
Fish are an excellent source of protein, are low in saturated fats, and contain omega-3 fatty acids. Because nearly all fish and shellfish contain trace amounts of mercury, pregnant and lactating women are advised to avoid specific types of fish with potentially high methylmercury levels. These include shark, swordfish, king mackerel, and tile fish. It is further recommended that pregnant women ingest no more than 12 ounces or two servings of canned tuna per week and no more than 6 ounces of albacore or “white” tuna (United States Environmental Protection Agency, 2004). If the mercury content of locally caught fish is unknown, then overall fish consumption should be limited to 6 ounces per week (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). The Avon Longitudinal Study of Parents and Children, however, reported beneficial effects on pregnancy outcomes in women who consumed 340 g or more of seafood weekly (Hibbeln, 2007).
Maternal lead exposure has been associated with several adverse maternal and fetal outcomes across a range of maternal blood lead levels (Bellinger, 2005). These include gestational hypertension, spontaneous abortion, low birthweight, and neurodevelopmental impairments in exposed fetuses (American College of Obstetricians and Gynecologists, 2012b). The exposure levels at which these risks increase remains unclear. But, recognizing that such exposure remains a significant health issue for reproductive-aged women, the Centers for Disease Control and Prevention (2010a) has issued guidelines for screening and managing exposed pregnant and lactating women. These guidelines, which have been endorsed by the American College of Obstetricians and Gynecologists (2012b), recommend blood lead testing only if a risk factor is identified (Table 9-8). If the levels are > 5 μg/dL, then counseling is completed, and the lead source is sought and removed. Subsequent blood levels should be obtained. Blood lead levels ≥ 45 μg/dL are consistent with lead poisoning, and women in this group may be candidates for chelation therapy. Such pregnancies should be managed in consultation with lead poisoning treatment experts. National and state resources are available at the CDC website: www.cdc.gov/nceh/lead.
TABLE 9-8. Risk Factors for Lead Exposure in Pregnant and Lactating Women
Recent immigration from or residency in areas of high ambient lead contamination
Living near a point source of lead
Working with lead or living with someone who does
Using lead-glazed ceramic pottery
Eating nonfood substances (pica)
Using alternative or complementary medicines, herbs, or therapies
Using imported cosmetics or certain food products
Renovating or remodeling older homes without implementing lead hazard controls
Consuming lead-contaminated drinking water
Having a prior lead-exposure history or evidence of an elevated body burden of lead
Living with someone identified with an elevated lead level
Adapted from Centers for Disease Control and Prevention, 2010a.
Automobile and Air Travel
The American College of Obstetricians and Gynecologists (2010) has formulated guidelines for automobile passenger restraints use during pregnancy (Chap. 47, p. 951). Women should be encouraged to wear properly positioned three-point restraints throughout pregnancy while riding in automobiles. The lap portion of the restraining belt should be placed under the abdomen and across her upper thighs. The belt should be comfortably snug. The shoulder belt also should be firmly positioned between the breasts. Available information suggests that airbags should not be disabled for the pregnant woman.
In general, air travel in a properly pressurized aircraft has no harmful effect on pregnancy (Aerospace Medical Association, 2003). Thus, in the absence of obstetrical or medical complications, the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2009a, 2012) have concluded that pregnant women can safely fly up to 36 weeks’ gestation. It is recommended that pregnant women observe the same precautions for air travel as the general population. These include seatbelt use while seated and periodic lower extremity movement and at least hourly ambulation to lower venous thromboembolism risks. Significant risks with travel, especially international travel, are infectious disease acquisition and development of complications remote from adequate resources (Ryan, 2002).
In healthy pregnant women, sexual intercourse usually is not harmful. Whenever abortion, placenta previa, or preterm labor threatens, however, coitus should be avoided. Nearly 10,000 women enrolled in a prospective investigation by the Vaginal Infection and Prematurity Study Group were interviewed regarding sexual activity (Read, 1993). They reported a decreased frequency of sexual intercourse with advancing gestation. By 36 weeks, 72 percent had intercourse less than once weekly. According to Bartellas and colleagues (2000), the decline is attributed to decreased desire in 58 percent and fear of harm to the pregnancy in 48 percent.
Intercourse late in pregnancy specifically has not been found to be harmful. Grudzinskas and coworkers (1979) found no association between gestational age at delivery and coital frequency during the last 4 weeks of pregnancy. Sayle and colleagues (2001) found no increased—and actually a decreased—risk of delivery within 2 weeks of intercourse. Tan and associates (2007) studied women scheduled for nonurgent labor induction and found that spontaneous labor ensued at equal rates in groups either participating in or abstaining from intercourse.
Oral-vaginal intercourse is occasionally hazardous. Aronson and Nelson (1967) described a fatal air embolism late in pregnancy as a result of air blown into the vagina during cunnilingus. Other near-fatal cases have been described (Bernhardt, 1988).
Examination of the teeth should be included in the prenatal examination, and good dental hygiene is encouraged. Indeed, periodontal disease has been linked to preterm labor. Unfortunately, although its treatment improves dental health, it has not prevented preterm birth (Michalowicz, 2006). Dental caries are not aggravated by pregnancy. Importantly, pregnancy is not a contraindication to dental treatment including dental radiographs (Giglio, 2009).
Current recommendations for immunization during pregnancy are summarized in Table 9-9. Well-publicized concerns regarding a causal link between childhood exposure to the thimerosal preservative in some vaccines and neuropsychological disorders has led to some parental prohibition. Although controversy continues, these associations have proven groundless (Sugarman, 2007; Thompson, 2007; Tozzi, 2009). Thus, many vaccines may be used in pregnancy. The American College of Obstetricians and Gynecologists (2013c) stresses the importance of integrating an effective vaccine strategy into the care of both obstetrical and gynecological patients. The College further emphasizes that information on the safety of vaccines given during pregnancy is subject to change and recommendations can be found from the Centers for Disease Control and Prevention website at: www.cdc.gov/vaccines.
TABLE 9-9. Recommendations for Immunization During Pregnancy
The frequency of pertussis infection has substantially increased in the United States. This resulted in updated recommendations for use of the three-agent Tdap vaccine—tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Centers for Disease Control and Prevention, 2013a). Young infants are at increased risk for death from pertussis and are entirely dependent on passive immunization from maternal antibodies until the vaccine series is initiated at 2 months of age. As demonstrated by Healy and coworkers (2013), maternal antipertussis antibodies are relatively short-lived, and Tdap administration before pregnancy—or even in the first half of the current pregnancy—is not likely to provide a high level of newborn antibody protection. The Advisory Committee on Immunization Practices, therefore, has recommended that a dose of Tdap be given to women during each pregnancy, optimally between 27 and 36 weeks’ gestation to maximize passive antibody transfer to the fetus (Centers for Disease Control and Prevention, 2013a). The American College of Obstetricians and Gynecologists supports this recommendation (2012j).
All women who will be pregnant during influenza season should be offered vaccination, regardless of gestational age. Those with underlying medical conditions that increase the risk for complications should be provided the vaccine before flu season starts (American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 2012). Zaman and colleagues (2008) showed that prenatal maternal vaccination reduced the infant influenza incidence in the first 6 months of life by 63 percent in infants born to these treated women. Moreover, it reduced all febrile respiratory illnesses in these infants by a third.
Women who are susceptible to rubella during pregnancy should receive MMR—measles, mumps, rubella—vaccination postpartum. Although this vaccine is not recommended during pregnancy, congenital rubella syndrome has never resulted from its inadvertent use. There is no contraindication to MMR vaccination while breast feeding (Centers for Disease Control and Prevention, 2011).
Biological Warfare and Vaccines
The ongoing threat of bioterrorism requires familiarity with smallpox and anthrax vaccines during pregnancy. The smallpox vaccine is made with live attenuated vaccinia virus, which is related to smallpox and cowpox viruses. Fetal vaccinia infection is rare, but it may result in abortion, stillbirth, or neonatal death. Thus, in nonemergency circumstances, vaccination is contraindicated during pregnancy and in women who might become pregnant within 28 days of vaccination (Centers for Disease Control and Prevention, 2013c). But, if vaccination is inadvertently administered in early pregnancy, this is not an indication for termination (Suarez, 2002). If the pregnant woman is at risk because of exposure to smallpox—either as a direct victim of a bioterrorist attack or as a close contact of an individual case—the risks from clinical smallpox substantially outweigh any potential risk from vaccination.
Anthrax vaccination has been limited principally to individuals who are occupationally exposed, such as special veterinarians, laboratory workers, and military personnel. The vaccine contains no live bacteria and thus would not be expected to pose significant fetal risk. Wiesen and Littell (2002) studied the reproductive outcomes of 385 women in the United States Army who became pregnant after vaccination and reported no adverse effects on fertility or pregnancy outcome. Smallpox, anthrax, and other infections related to bioterrorism are discussed in Chapter 64 (p. 1258).
Whether adverse pregnancy outcomes are related to caffeine consumption is somewhat controversial. As summarized from Chapter 18 (p. 353), heavy intake of coffee each day—about five cups or 500 mg of caffeine—slightly increases the abortion risk. Studies of “moderate” intake—less than 200 mg daily—did not report increased risk.
It is unclear if caffeine consumption is associated with preterm birth or impaired fetal growth. Clausson and coworkers (2002) found no association between moderate caffeine consumption of less than 500 mg daily and low birthweight, fetal-growth restriction, or preterm delivery. Bech and associates (2007) randomly assigned more than 1200 pregnant women who drank at least three cups of coffee per day to caffeinated versus decaffeinated coffee. They found no difference in birthweight or gestational age at delivery between groups. The CARE Study Group (2008), however, evaluated 2635 low-risk pregnancies and reported a 1.4-fold risk for fetal-growth restriction among those whose daily caffeine consumption was > 200 mg compared with those who consumed < 100 mg daily. The American College of Obstetricians and Gynecologists (2013d) has concluded that moderate consumption of caffeine—less than 200 mg per day—does not appear to be associated with miscarriage or preterm birth, but that the relationship between caffeine consumption and fetal-growth restriction remains unsettled. The American Dietetic Association (2008) recommends that caffeine intake during pregnancy be limited to less than 300 mg daily, or approximately three 5-oz cups of percolated coffee.
Nausea and Vomiting
These are common complaints during the first half of pregnancy. Nausea and vomiting of varying severity usually commence between the first and second missed menstrual period and continue until 14 to 16 weeks’ gestation. Although nausea and vomiting tend to be worse in the morning—thus erroneously termed morning sickness—both symptoms frequently continue throughout the day. Lacroix and coworkers (2000) found that nausea and vomiting were reported by three fourths of pregnant women and lasted an average of 35 days. Half had relief by 14 weeks, and 90 percent by 22 weeks. In 80 percent of these women, nausea lasted all day.
Treatment of pregnancy-associated nausea and vomiting seldom provides complete relief, but symptoms can be minimized. Eating small meals at more frequent intervals but stopping short of satiation is valuable. Borrelli and colleagues (2005) performed a systematic literature search and reported that the herbal remedy ginger was likely effective. Mild symptoms usually respond to vitamin B6 given along with doxylamine, but some women require phenothiazine or H1-receptor blocking antiemetics (American College of Obstetricians and Gynecologists, 2013e). In some, hyperemesis gravidarum develops—vomiting so severe that dehydration, electrolyte and acid-base disturbances, and starvation ketosis become serious problems. Its management and that of less severe nausea are described in Chapter 54 (p. 1072).
Low back pain to some extent is reported by nearly 70 percent of pregnant women (Wang, 2004). Minor degrees follow excessive strain or significant bending, lifting, or walking. It can be reduced by squatting rather than bending when reaching down, by using a pillow back support when sitting, and by avoiding high-heeled shoes. Back pain complaints increase with progressing gestation and are more prevalent in obese women and those with a history of low back pain. In some cases, troublesome pain may persist for years after the pregnancy (Norén, 2002).
Severe back pain should not be attributed simply to pregnancy until a thorough orthopedic examination has been conducted. Severe pain also has other uncommon causes, such as pregnancy-associated osteoporosis, disc disease, vertebral osteoarthritis, or septic arthritis (Smith, 2008). More commonly, muscular spasm and tenderness are classified clinically as acute strain or fibrositis. Although evidence-based clinical research directing care in pregnancy is limited, such low back pain usually responds well to analgesics, heat, and rest. Tylenol may be used chronically as needed. Nonsteroidal antiinflammatory drugs may also be beneficial but are used only in short courses to avoid fetal effects (Chap. 12, p. 247). Muscle relaxants that include cyclobenzaprine (Flexeril) or baclofen may be added when needed. Once acute pain is improved, stabilizing and strengthening exercises provided by physical therapy improve spine and hip stability, which is essential for the increased load of pregnancy. For some, a sacroiliac joint stabilizing support belt may be beneficial. There may also be a role for chiropractic manipulation in selected women. George and associates (2013) randomized 169 women with low back pain at 24 to 28 weeks’ gestation to standard obstetrical care or standard care plus multimodal therapy—a combination of manual chiropractic therapy, exercises, and patient education. The patients who received the multimodal therapy experienced significantly less pain, less disability, and greater global improvement in daily activities.
Varicosities and Hemorrhoids
Venous leg varicosities have a congenital predisposition and accrue with advancing age. They can be aggravated by factors that cause increased lower extremity venous pressures. As discussed in Chapter 4 (p. 60), femoral venous pressures in the supine pregnant woman increase from 8 mm Hg early to 24 mm Hg at term. Thus, susceptible women develop leg varicosities that typically worsen as pregnancy advances, especially with prolonged standing. Symptoms vary from cosmetic blemishes and mild discomfort at the end of the day to severe discomfort that requires prolonged rest with feet elevation. Treatment is generally limited to periodic rest with leg elevation, elastic stockings, or both. Surgical correction during pregnancy generally is not advised, although rarely the symptoms may be so severe that injection, ligation, or even stripping of the veins is necessary.
Vulvar varicosities frequently coexist with leg varicosities, but they may appear without other venous pathology. Uncommonly, they become massive and almost incapacitating. If these large varicosities rupture, blood loss may be severe. Treatment is with specially fitted pantyhose that will also minimize lower extremity varicosities. With particularly bothersome vulvar varicosities, a foam rubber pad suspended across the vulva by a belt can be used to exert pressure on the dilated veins.
Hemorrhoids are rectal vein varicosities and may first appear during pregnancy as pelvic venous pressures increase. Commonly, they are recurrences of previously encountered hemorrhoids. Pain and swelling usually are relieved by topically applied anesthetics, warm soaks, and stool-softening agents. With thrombosis of an external hemorrhoid, there can be considerable pain. This may be relieved by incision and removal of the clot under local analgesia.
This symptom is one of the most common complaints of pregnant women and is caused by gastric content reflux into the lower esophagus. The increased frequency of regurgitation during pregnancy most likely results from upward displacement and compression of the stomach by the uterus, combined with relaxation of the lower esophageal sphincter (Chap. 4, p. 66). In most pregnant women, symptoms are mild and are relieved by a regimen of more frequent but smaller meals and avoidance of bending over or lying flat. Antacids may provide considerable relief. Aluminum hydroxide, magnesium trisilicate, or magnesium hydroxide alone or in combination are given. Management for symptoms that do not respond to these simple measures is discussed in Chapter 54 (p. 1072).
Pica and Ptyalism
The craving of pregnant women for strange foods is termed pica. At times, nonfoods such as ice—pagophagia, starch—amylophagia, or clay—geophagia may predominate. This desire has been considered by some to be triggered by severe iron deficiency. Although such cravings usually abate after iron deficiency correction, not all pregnant women with pica are iron deficient. Indeed, if strange “foods” dominate the diet, iron deficiency will be aggravated or will develop eventually.
Patel and coworkers (2004) from the University of Alabama at Birmingham prospectively completed a dietary inventory on more than 3000 women during the second trimester. The prevalence of pica was 4 percent. The most common nonfood items ingested were starch in 64 percent, dirt in 14 percent, sourdough in 9 percent, and ice in 5 percent. The prevalence of anemia was 15 percent in women with pica compared with 6 percent in those without it. Interestingly, the rate of spontaneous preterm birth before 35 weeks was twice as high in women with pica.
Women during pregnancy are occasionally distressed by profuse salivation—ptyalism. Although usually unexplained, ptyalism sometimes appears to follow salivary gland stimulation by the ingestion of starch.
Sleeping and Fatigue
Beginning early in pregnancy, many women experience fatigue and need increased amounts of sleep. This likely is due to the soporific effect of progesterone but may be compounded in the first trimester by nausea and vomiting and in the latter stages of pregnancy by general discomforts, urinary frequency, and dyspnea. Moreover, sleep efficiency appears to progressively diminish as pregnancy advances. Wilson and associates (2011) performed overnight polysomnography in 27 women in the third trimester, in 21 women in the first trimester, and in 24 nonpregnant control women. Women in the third trimester had poorer sleep efficiency, more awakenings, and less of both stage 4 (deep) and rapid-eye movement sleep. Women in the first trimester were also affected but to a lesser extent. Subjective assessments of sleep quality have yielded similar findings. Facco and colleagues (2010) prospectively evaluated 189 healthy nulliparous women with a sleep survey completed once before midpregnancy and again in the third trimester. They found that women in the third trimester had significantly shorter sleep durations and were more likely to snore and meet criteria for restless leg syndrome. Most women experience some degree of sleep disturbance by the third trimester. Daytime naps and mild sedatives at bedtime such as diphenhydramine (Benadryl) can be helpful.
Pregnant women commonly develop increased vaginal discharge that in many instances is not pathological. Increased mucus secretion by cervical glands in response to hyperestrogenemia is undoubtedly a contributing factor. Occasionally, troublesome leukorrhea is the result of vulvovaginal infection. In the adult woman, most of these are bacterial vaginosis, candidiasis, or trichomoniasis, which are reviewed in Chapter 65 (p. 1276).
Cord Blood Banking
Since the first successful cord blood transplantation in 1988, more than 25,000 umbilical cord blood transplantations have been performed to treat hemopoietic cancers and various genetic conditions (Butler, 2011). There are two types of cord blood banks. Public banks promote allogeneic donation, for use by a related or unrelated recipient, similar to blood product donation. Private banks were initially developed to store stem cells for future autologous use and charged fees for initial processing and annual storage. The American College of Obstetricians and Gynecologists (2012d) has concluded that if a woman requests information on umbilical cord banking, information regarding advantages and disadvantages of public versus private banking should be explained. Some states have passed laws that require physicians to inform patients about cord blood banking options. Importantly, few transplants have been performed by using cord blood stored in the absence of a known indication in the recipient (Thornley, 2009). The likelihood that cord blood would be used for the child or family member of the donor couple is considered remote and estimated to be about 1 in 2700 individuals (American College of Obstetricians and Gynecologists, 2008). It is recommended that directed donation be considered when an immediate family member carries the diagnosis of a specific condition known to be treatable by hemopoietic transplantation.
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