Mayo Clinic Guide to a Healthy Pregnancy: From Doctors Who Are Parents, Too!

CHAPTER 5. Month 2: Weeks 5 to 8

It’s probably a cliché but when it happens to you, inside you, it’s really amazing and it feels like a miracle. What I keep thinking is, wow, how does it know how to do all this? This tiny little embryo inside me knows how to grow, feed, how to multiply and divide itself to form tiny heart, lungs, arms, legs, etc. If I had to remember things like “Oh, I should make sure I give the baby the ability to see, breathe, and bend his arms…,” it would be a disaster! Instead, I keep living my life happily clueless, while this supercomplex miracle is happening right inside my belly. — Lilli

OK, the first couple weeks of your pregnancy were pretty much a breeze. In fact, they were kind of fun — all of the excitement that comes with finding out the big news. Well, get prepared, this month things are going to change. You’ll soon begin to “feel” like you’re pregnant. Month two is when most women experience extreme tiredness and fatigue. You may also find yourself making countless trips to the bathroom and walking around all day with that nauseous feeling.

BABY’S GROWTH

During weeks five through eight of your pregnancy, your baby’s cells multiply rapidly and they begin to perform specific functions. This process of specialization is called differentiation. It’s necessary to produce all the different cells that make up a human being. As a result of differentiation, your baby’s main external features also will begin to take shape.

Week 5 No longer just a mass of cells, your baby — now officially called an embryo — is starting to take on a distinct form. The embryo has divided into three layers. In the top layer, a groove develops and then closes to form the neural tube, which will eventually develop into your baby’s brain, spinal cord, spinal nerves and backbone. This groove runs along the midline of the body, from the top to the bottom of the embryo. The closure of the neural tube begins in the embryo’s midsection. It proceeds upward and downward from there, like a double zipper. The top portion thickens to begin forming the brain.

From the embryo’s middle layer of cells, the heart and the circulatory system are taking shape. A bulge at the center of the embryo will develop into your baby’s heart. By week’s end, the earliest blood elements and blood vessels have formed, both in the embryo and the developing placenta. Your baby’s first heartbeats occur at 21 to 22 days after conception. You and your care provider can’t hear them yet, but it may be possible to see the beating motion on an ultrasound. With these changes, circulation begins, making the circulatory system the first functioning organ system.

Your baby also has an inner layer of cells, from which lungs, intestines and the urinary bladder will develop. This week, not much is happening in the inner layer. It will be awhile yet before those areas take shape.

At the moment of conception, your baby was a single-celled zygote and was microscopic in size. By the fifth week of your pregnancy, three weeks after conception, your baby is about  of an inch long, which is about the size of the tip of a pen.

Week 6 Growth is rapid during the sixth week, during which your baby will triple in size. Formation of baby’s facial features is in its early stages. Optic vesicles, which later form the eyes, are beginning to develop. Passageways that will make up the inner ear also are beginning to form. An opening for the mouth is formed by the ingrowth of tissue from above and from the sides of the face. Below the mouth, where the neck will develop, are small folds that ultimately will become your baby’s neck and lower jaw.

By the sixth week of your pregnancy the neural tube along your baby’s back has closed over. The brain is growing rapidly to fill the now-formed, enlarging head. Your baby’s brain is also developing distinct regions.

In the front of the chest, your baby’s heart is pumping rudimentary blood through the main blood vessels and beating at a regular rhythm. The beginnings of the digestive and respiratory systems are forming. In addition, 40 small blocks of tissue are developing along your baby’s midline. These will form the connective tissue, ribs and muscles of your baby’s back and sides. Small buds that will grow into your baby’s arms and legs are now visible.

By the sixth week of your pregnancy, four weeks after conception, your baby is about ⅛ of an inch long.

Week 7 This week the umbilical cord, the vital link between your baby and your placenta, is clearly visible starting near the site where your baby implanted in your uterus. The umbilical cord contains two arteries and one large vein. Nutrients and oxygen-rich blood pass from your placenta to your baby by way of the single vein and then back to your placenta through the two arteries. It takes about 30 seconds for a blood cell to make the entire trip.

In addition, your baby’s brain is becoming more complex. Cavities and passages necessary for circulation of spinal fluid have formed. Your baby’s growing skull is still transparent. If you were able to get a look at it under a magnifying glass, you might see the smooth surface of your baby’s tiny, developing brain.

Baby’s face is taking on more definition this week. A mouth perforation, tiny nostrils, ear indentations and color in the irises of the eyes are now visible. The lenses of baby’s eyes are forming and the middle portions of the ears are connecting the inner ear to the outer world.

Your baby’s arms, legs, hands and feet are taking shape, though the beginnings of fingers and toes are about a week away. The arm bud that sprouted just last week has already developed into a shoulder portion and a hand portion, which looks like a tiny paddle.

At seven weeks into your pregnancy, your baby is ⅓ of an inch long, a little bigger than the top of a pencil eraser.

Week 8 Your baby’s fingers and toes begin to form this week, although they’re still webbed. His or her tiny arms and legs are growing longer and more defined. Paddle-shaped foot and hand areas are evident. Wrists, elbows and ankles are clearly visible. Your baby may even be able to flex at the elbows and wrists.

The eyelids also are forming. Until they’re done growing, your baby’s eyes will appear open. This is also the week your baby’s ears, upper lip and tip of the nose begin taking on recognizable form.

Your baby’s digestive tract is continuing to grow, especially the intestines. Heart function and circulation are now more fully developed. Your baby’s heart is pumping at about 150 beats a minute, about twice the adult rate.

At the eighth week of your pregnancy, your baby is just over 1/25 of an inch long.

WHAT TO AVOID

Your developing baby is most vulnerable during weeks five through 10 of your pregnancy. During this time, all of baby’s major organs are forming, and injury to the embryo could result in a major birth defect. Things that have the potential to cause damage include:

 Teratogens. Examples of these harmful substances include alcohol, certain medications and recreational drugs. Avoid them.

 Infections. Viruses and bacteria can potentially harm your baby in early pregnancy. A baby can only acquire infections through the mother, but you may not even feel ill with some of the conditions that can cause serious defects. Immunization and natural immunity protects you against many potentially harmful infections. Still, it makes sense to take appropriate precautions to avoid exposure to illnesses such as chickenpox, measles, mumps, German measles (rubella) or cytomegalovirus (CMV).

 Radiation. High doses of ionizing radiation, such as radiation therapy for cancer, can harm your baby. Low doses of radiation, on the other hand, such as those used in a diagnostic X-ray, generally don’t pose a significant increase in the risk of birth defects. However, to be on the safe side, when you’re pregnant it’s best not to have an X-ray unless it’s necessary, just as you wouldn’t undergo any medical procedure or take medications unless it’s necessary. If you have a serious health problem where an X-ray can provide important information, it’s probably best to do it. Talk with your care provider. Unless it’s very extensive, diagnostic X-rays may be more helpful than harmful, even in early pregnancy. If you had an X-ray before you knew you were pregnant, don’t be alarmed. It’s highly unlikely the fetus received enough radiation to cause any problems.

 Poor nutrition. Extremely poor eating habits during pregnancy can harm your baby. Eating too little of a specific nutrient may impact cell development. However, the early embryo isn’t likely to be harmed by a lack of calories, even if nausea and vomiting limit your daily calories. Be sure to take a vitamin supplement daily that contains at least 400 micrograms of folic acid. This will reduce your baby’s risk of developing spina bifida or other neural tube defects.

YOUR BODY CHANGES

The second month of pregnancy brings enormous changes for your body. It’s the time you’re likely to experience the discomforts and annoyances of early pregnancy, such as nausea, heartburn, fatigue, insomnia and frequent urination. But don’t let these symptoms get you down. Think of them as signs that your pregnancy is proceeding normally.

What’s happening and where?

Hormones are the chemical messengers that regulate many aspects of your pregnancy, and this month your hormones kick into high gear. Hormones released throughout your pregnancy do two things. They influence the growth of your baby, and they send signals that change the way your organs function. In fact, the hormonal changes of pregnancy affect nearly every part of your body.

Digestion Nausea and vomiting, commonly referred to as morning sickness, may be the most significant hormone-related change you’ll experience this month. Exactly what causes the nausea and vomiting for morning sickness isn’t known, but changes in your gastrointestinal system in response to high hormone levels almost certainly play a role. Increased progesterone slows down the pace at which your food passes through your digestive tract. Therefore, your stomach empties somewhat more slowly, which may make you more likely to have nausea and vomiting. Estrogen may also have a direct effect on the brain, which triggers nausea. Morning sickness is discussed below.

Heart and circulatory system Your body continues to produce more blood to carry oxygen and nutrients to your baby. This increase in blood production, which continues throughout your pregnancy, will be especially high this month and next, due to enormous demands on your circulation. Despite this effort, your blood vessels are dilating even more quickly and your circulation is just a bit short of blood volume. To accommodate these changes, your heart continues to pump harder and faster. These changes in blood circulation can cause signs and symptoms such as fatigue, dizziness and headaches.

Breasts Stimulated by increased production of estrogen and progesterone, your breasts continue to enlarge as the milk-producing glands inside them grow in size. You may also notice that your areolas, the rings of brown or reddish-brown skin around your nipples, are starting to enlarge and darken. This is the result of increased blood circulation. Your breasts may feel tender, tingly or sore. Or they may feel fuller and heavier.

Uterus If this is your first pregnancy, your uterus used to be about the size of a pear. Now it’s starting to expand. By the time you deliver your baby, it will have expanded to about 1,000 times its original size. Through this month and the next, your uterus will still fit inside your pelvis. However, its increasing size may cause you to feel the need to urinate more often. You may also leak urine when you sneeze, cough or laugh. This is a simple matter of geography. During the first few months of pregnancy, your bladder lies directly in front and slightly under your uterus. As your uterus grows, your bladder gets crowded.

The placenta also is continuing to grow and secure its attachment to the uterus. Sometimes this results in minor bleeding, which usually is normal. But if this does happen, let your care provider know about it.

SPOTTING

You may experience some vaginal bleeding during the first 12 weeks of your pregnancy. Statistics indicate that as many as 25 percent of pregnant women may have some bleeding (spotting). However, statistics also indicate that only about half these women will have miscarriages. For more information on spotting and vaginal bleeding, see the Symptoms guide.

THE ‘WARMED-UP’ EFFECT

If you’ve been pregnant once before, you may notice that you’re bigger than you were at the same time during your last pregnancy. You may also notice that side effects seem to be happening earlier this time.

You could call this the warmed-up effect. Like a balloon that’s easier to blow up the second or third time around, your uterus may expand more quickly and easily once it has been through one pregnancy. Your abdominal muscles and ligaments have already been stretched once, so they give more easily as your uterus expands on the second go-round.

The downside is that because your uterus is getting bigger faster, you may experience symptoms such as pelvic pressure and back pain sooner in this pregnancy than you did in your first pregnancy.

Cervix This month, your cervix turns a bluish tinge and continues to soften. Over the course of your pregnancy, your cervix will gradually become softer as it prepares for the thinning (effacement) and opening (dilation) necessary for childbirth. By the seventh week of pregnancy, the mucous plug is well established in your cervix. This structure blocks the cervical canal during pregnancy, to prevent germs from getting into your uterus. The plug loosens and passes late in pregnancy, typically when your cervix starts to thin out and open in preparation for labor.

CAN STRESS CAUSE MISCARRIAGE?

Stress has long been suspected as a possible cause of early miscarriage, but there’s little evidence to support the theory. An estimated 10 to 20 percent of known pregnancies end in miscarriage. Typically, early miscarriage is caused by a fetal chromosomal abnormality or another problem in the development of the embryo. Other causes of repeated early miscarriage may include:

 Chromosomal abnormalities in either parent

 Blood-clotting problems

 Abnormalities of the uterus or cervix

 Hormone imbalances

 Immune responses that disrupt implantation

If you’re concerned about early miscarriage, concentrate on taking good care of yourself and your baby and avoid known risk factors for miscarriage — such as smoking and drinking alcohol.

COPING WITH MORNING SICKNESS

Morning sickness is one of the dreaded aspects of pregnancy. If you’re lucky, you’ll escape it, but most women don’t. Morning sickness refers to the nausea that occurs during pregnancy. The name is a misnomer, however, because the condition isn’t limited to mornings. It can strike at any time of the day or night.

Morning sickness affects an estimated 50 to 90 percent of pregnant women. It’s most common during the first trimester and is characterized by nausea with or without vomiting. Signs and symptoms typically start at five to eight weeks, sometimes beginning as early as two weeks after conception. They often subside by weeks 13 to 14; however, some women experience morning sickness well beyond the first trimester.

Treatment isn’t usually needed for morning sickness — although home remedies, such as snacking throughout the day and sipping ginger ale, can help relieve nausea. Rarely, morning sickness is so severe that it’s classified as hyperemesis gravidarum, which can require hospitalization and treatment with intravenous (IV) fluids and medications.

Hormones and more What causes morning sickness isn’t entirely clear, but the hormonal changes of pregnancy are thought to play a significant role. The condition can affect any pregnant woman, but you might be more likely to experience morning sickness if:

 You experienced nausea or vomiting from motion sickness, migraines, certain smells or tastes, or exposure to estrogen (in birth control pills, for example) before pregnancy

 You experienced morning sickness during a previous pregnancy

 You’re pregnant with twins or other multiples

Studies suggest that women who experience morning sickness are less likely to have early pregnancy loss. However, this doesn’t mean that if you don’t experience morning sickness you’re at risk of miscarriage. Some women simply seem to be more immune to the nauseating effects that accompany a rise in pregnancy hormones.

How to ease the queasiness To help relieve morning sickness:

 Choose foods carefully. Opt for foods that are high in carbohydrates, low in fat and easy to digest. Salty foods are sometimes helpful, as are foods that contain ginger — such as ginger lollipops. Avoid greasy, spicy and fatty foods.

 Snack often. Before getting out of bed in the morning, eat a few soda crackers or a piece of dry toast. Nibble throughout the day, rather than eating three larger meals. An empty stomach may aggravate nausea.

 Drink plenty of fluids. Sip water or ginger ale. It may also help to suck on hard candy, ice chips or ice pops.

 Pay attention to triggers. Avoid foods or smells that seem to make your nausea worse. Keep rooms well ventilated and free of cooking odors, which can aggravate nausea.

 Get plenty of fresh air. Weather permitting, open the windows in your home or workplace. Take a daily walk outdoors.

 Take care with prenatal vitamins. If you feel queasy after taking prenatal vitamins, take the vitamins at night or with a snack. It may also help to chew gum or suck on hard candy after taking your prenatal vitamin. If these steps don’t help, ask your care provider if it might be possible to switch to a type of prenatal vitamin that doesn’t contain iron.

 Experiment with acupressure and acupuncture. Although they haven’t been proven to be effective, some women find these therapies to be helpful in relieving morning sickness. Acupressure involves stimulating certain points on the body with pressure. Acupressure wristbands, available in pharmacies without a prescription, are designed to stimulate a certain point on the wrist. This action is thought to reduce nausea. Acupuncture involves inserting hair-thin needles into your skin. Some women find it helpful, but it requires an appointment with a licensed acupuncturist.

YOUR EMOTIONS

Pregnancy is a psychological journey as well as a biological one. You’re still the daughter of your parents. Yet soon you’ll be the mother of your own child. You’ll have a new role to play and a new identity. The emotions you’re feeling in the face of this reality can be both overwhelmingly positive and distressingly negative.

Anticipation Anticipation is a normal part of making the transition to parenthood. Beginning early in pregnancy, you start collecting information about how to be a good mother, based on the parenting you received as a child and your observations of other families you’ve encountered. The memories of how you were raised, along with your personal ideals of parenting, serve as a bank of images that you can draw from as you think ahead to what your own parenting style will be.

During this time of anticipation, you’ll probably have dreams and fantasies about what your baby will be like. These imaginings aren’t a waste of time. They’re the beginnings of your emotional bond with your baby.

Worries and concerns During your second month of pregnancy, the excitement you felt when you learned you were pregnant may be dampened by fear. What if you might have done something to harm your baby before you knew you were pregnant? What about that aspirin you took for a headache? Or that glass of wine you had with dinner? Or that bout of the flu? If you have concerns, share them with your care provider. Doing so may help put your mind at ease.

You may also be worried about other things. How will you cope with your pregnancy? Will you have problems at your job? Can you handle the pain of labor and delivery? Will your baby be healthy? Discuss these worries with your partner. If you hide them, worries can cause tension in your relationship. They can create a sense of distance between you and your partner at a time when you both need the warmth of a close, loving relationship.

Some women experience disturbing, anxiety-provoking dreams or feelings during early pregnancy. These thoughts may seem senseless or irrational, yet they’re normal and very common. For most new parents, such thoughts usually pass. However, if troubling thoughts and feelings persist and you find them disturbing, consider talking to your care provider, who may refer you to a therapist or counselor to help you manage such thoughts.

PRENATAL CHECKUP

The time is finally here to see your care provider. Your first prenatal checkup is an exciting time. This will likely be your longest and most comprehensive checkup. Therefore, allow plenty of time in your schedule — up to three hours — so that you won’t feel rushed. You’ll probably meet several different people, including nurses and office staff.

Your first prenatal visit with your care provider gives you a chance to review your general health and lifestyle and talk honestly about being pregnant and giving birth. To get the most out of your first visit, keep the following tips in mind:

 Be proactive. Discuss ways you might improve your lifestyle to ensure the healthiest possible pregnancy. Possible topics to cover include your diet, exercise, smoking and alcohol use.

 Don’t hold back. Raise any concerns or fears you may have about your pregnancy and childbirth. The sooner these fears and concerns are addressed, the sooner you can have peace of mind.

 Be honest. Tell the truth when talking with your care provider. The quality of care you receive depends in large part on the quality of the information you provide.

FIRST APPOINTMENT CHECKLIST

Discussion of your medical history at your first appointment with your care provider will likely cover the following topics:

 Details of any previous pregnancies

 The typical length of time between your periods

 The first day of your last period

 Your use of contraceptives

 Prescription or over-the-counter medications you’re taking

 Allergies you have

 Medical conditions or diseases you have had or now have

 Past surgeries, if any

 Your work environment

 Your lifestyle behaviors, such as exercise, diet, smoking or exposure to secondhand smoke, and the use of alcoholic beverages or recreational drugs

 Risk factors for sexually transmitted diseases — such as you or your partner having more than one sexual partner

 Past or present medical problems, such as diabetes, high blood pressure (hypertension), lupus or depression, in your or your partner’s immediate family — father, mother, siblings

 Family histories, on both sides, of babies with congenital abnormalities or genetic diseases

 Details on your home environment, such as whether you feel safe and supported at home

What’s going to happen? Most women have prenatal visits every four to six weeks until their eighth month. Then the visits become more frequent. If you have a chronic health problem, such as diabetes or high blood pressure, you may need more frequent visits to monitor your health and your baby’s health.

Medical history Gathering as much information as possible about your past and present health is one of your care provider’s biggest goals during your first visit. He or she will review your past and current health, including any chronic medical conditions you have and problems you’ve had during past pregnancies. Come to your appointment prepared to answer questions about many aspects of your health and lifestyle.

While discussing your medical history, you’ll also have a chance to ask questions you may have about your pregnancy. If you’ve been keeping a running list of questions, bring it to your first appointment.

Physical exam The physical examination will likely include weight, height and blood pressure measurements, as well as an overall assessment of your general health. A pelvic exam also is an important part of this evaluation. A device called a speculum is used to examine your vagina. It allows for a clear view of your cervix, the opening to your uterus. Changes in your cervix and in the size of your uterus help your care provider determine how far along you are in your pregnancy.

While the speculum is still in place, your care provider may gently collect some cells and mucus from your cervix to perform a Pap test and to screen for infections. The Pap test helps detect abnormalities that indicate precancer or cancer of the cervix. Infections of the cervix such as the sexually transmitted diseases gonorrhea and chlamydia can affect your pregnancy and the health of your baby.

After removing the speculum, your care provider may insert two gloved fingers into your vagina to check your cervix and, with the other hand on top of your abdomen, check the size of your uterus and ovaries. This is done, in part, to evaluate the size of your birth canal during this exam. These measurements can help predict whether you might have problems during labor and delivery, though it’s difficult to make an accurate prediction at this early stage.

You may be apprehensive about having a pelvic exam. Many women are. During the exam, try to relax as much as you can. Breathe slowly and deeply. If you tense up, your muscles can tighten, which can make the exam more uncomfortable. Remember, a typical pelvic exam takes only a couple of minutes.

Expect that you may have some vaginal bleeding after your pelvic exam and Pap test, especially within 24 hours of your visit. The bleeding may be just some light spotting, or it may be a little heavier. It usually goes away within a day. This happens because the cervix, which has already begun to soften due to pregnancy, is more inclined to bleed after a Pap test. The bleeding is from the outside of your cervix and isn’t a risk to your baby. If you’re concerned about it, talk to your care provider.

Lab tests Routine laboratory tests during your first prenatal visit include blood tests to determine your blood type (A, B, AB or O) and rhesus (Rh) factor — Rh positive or Rh negative — and to determine if you still have immunity to certain diseases from previous vaccinations, such as German measles (rubella) or hepatitis B.

Your blood is also screened for red blood cell antibodies — most commonly, Rh antibodies. These types of antibodies can increase your baby’s risk of developing anemia and jaundice after birth. You’ll also be offered a test for human immunodeficiency virus (HIV), the virus that causes AIDS. Tests for immunity to chickenpox, measles, mumps and toxoplasmosis may be done as well. Some women may be screened for thyroid problems. It typically takes just one needle stick and one blood sample to run all of these tests.

You may also be asked to provide a urine sample. An analysis of your urine can determine whether you have a bladder or kidney infection, which would require treatment. The urine sample can also be tested for increased sugar, indicating diabetes, and protein, indicating possible kidney disease.

An ultrasound exam also may be performed at your first visit if there are questions about how far along you are in your pregnancy, if the pregnancy may be ectopic (see ectopic pregnancy in Chapter 30), or if you may be carrying multiples.

TWINS, TRIPLETS, QUADS AND MORE

You may be ready for one baby, but what about two or three? For some women, this month’s visit to their care provider may bring surprising news that they’re expecting twins, triplets or even more, called multiple gestations.

Multiple babies are generally discovered at the time of your first ultrasound. The stage of pregnancy at which a woman receives her first ultrasound varies from one medical center to another. In some practices, an ultrasound is done at the first prenatal visit, in others it may not happen until the second or third visit. How early in your pregnancy you see your care provider also is a factor.

If your care provider performs an ultrasound at your first visit and you’re more than a couple of weeks into your pregnancy, it’s possible you may find out very early that you’re carrying multiples. An ultrasound can detect most multiples by the eighth week of pregnancy, possibly sooner. During an ultrasound examination, sound waves create an image of your uterus and your baby — or babies.

Physical signs of a multiple pregnancy include a uterus that’s larger than normal or extreme fatigue and nausea. If your care provider suspects that you’re carrying multiple babies, he or she may perform an ultrasound exam to confirm these suspicions.

The number of women having multiples is on the rise, mainly for two reasons. First, more women over age 30 are having babies, and multiple births occur more frequently in women over 30. Second, the use of fertility drugs and assisted reproductive technologies is resulting in more multiple births.

How multiples are made There are two types of twins: identical and fraternal. Identical twins occur when a single fertilized egg splits and develops into two fetuses. Genetically, the two babies are identical. They will be the same sex and look exactly alike.

Fraternal twins occur when two separate eggs are fertilized by two different sperm. In this case, the twins can be two girls, two boys, or a boy and a girl. Genetically, the twins are no more alike than are any other siblings.

Early in pregnancy it’s possible to determine if twins are identical or fraternal with an ultrasound exam. The appearance of the placenta and membranes are key to making this determination.

Triplets can occur in several ways. In most cases, three separate eggs are produced by the mother and fertilized by three separate sperm. Another possibility is for a single fertilized egg to divide two ways, creating identical twins, with a second egg fertilized by a second sperm resulting in a fraternal third baby. It’s also possible for a single fertilized egg to divide three ways, resulting in three identical babies, although this is extremely rare.

Quads and greater numbers of multiples most often result from four or more eggs being fertilized by separate sperm. Use of fertility drugs or assisted reproductive techniques is generally involved.

What it means for mom If you’re carrying twins, triplets or other multiples, some side effects of pregnancy may be a bit more unpleasant. Nausea and vomiting, heartburn, insomnia and fatigue can be troublesome. Because of the increased space required by your growing babies, you may also have abdominal pain and shortness of breath. Later in your pregnancy, you may feel pressure on your pubic bone, the structure located over the lowest part of the front of your pelvis.

Carrying multiple babies means you’ll probably be seeing your care provider more often. Special care is often essential in multiple pregnancies. Your care provider may want to more closely track the growth of your babies and more closely monitor your health, anticipating potential problems before they occur.

With more than one baby to nourish, nutrition and weight gain also become more important. If you’re carrying twins, your care provider may recommend that you take in about 300 more calories a day. For twins, the American Congress of Obstetricians and Gynecologists recommends a weight gain of 37 to 54 pounds. However, if you were overweight before becoming pregnant, your recommended weight gain will be less. For additional multiples, the recommended weight gain will be higher, depending on the number of babies you’re carrying and your weight when you became pregnant.

A lowered blood cell count (anemia) is more likely with multiples. Therefore, your care provider may recommend that you take a supplement with 60 to 100 milligrams of elemental iron. You may also be asked to limit some of your activities, such as work, travel and exercise.

Possible complications Carrying more than one baby can increase your chances of some pregnancy complications. In most situations, multiple babies are born healthy, especially if you’re carrying twins. However, the more babies you carry, the greater the potential for complications. These may include:

Preterm labor When contractions begin to open the cervix before the 37th week of pregnancy, this is known as preterm labor. Nearly 60 percent of twins and more than 90 percent of triplets are born before the 37th week of pregnancy. The average gestational age of twins is 35 weeks. Triplets frequently arrive by 32 weeks, sometimes earlier. Almost all larger numbers of multiples come earlier.

Babies that arrive early have a greater chance of being low birth weight (less than 5½ pounds) and having other health complications. For that reason, your care provider will likely monitor you closely for signs of preterm labor. You’ll want to do the same.

Preeclampsia Preeclampsia is a condition that can develop during pregnancy, which includes elevated blood pressure. It is more common in mothers of multiples. Signs and symptoms of preeclampsia include rapid weight gain, headaches, abdominal pain, vision problems, and swelling of your hands and feet. It’s important to contact your care provider if you experience any of these problems.

Cesarean birth The chance of undergoing a C-section is higher with multiples. However, about half the women carrying twins have a vaginal birth. If you’re carrying more than two babies, your care provider may recommend a C-section as the safest delivery method for the babies.

Twin-twin transfusion This condition occurs only in identical twins. It can happen when a blood vessel in the placenta connects the circulatory systems of the two babies, and one twin receives too much blood flow and the other too little. A baby receiving too much may grow larger and develop an overload of blood in its circulatory system. The other twin may be smaller, grow more slowly and become anemic.

At times, early delivery of the twins may be necessary. Certain treatments also may help. Amniocentesis to drain off excess fluid may be beneficial. At some specialized hospitals, laser surgery is used to seal off the connection between the blood vessels.

Conjoined twins This occurs very rarely. Conjoined twins result from an incomplete division of identical twins. In the past, babies with this condition were commonly referred to as Siamese twins. Conjoined twins may be joined at the chest, head or pelvis. In some cases, the twins may share one or more internal organs. Surgery may be performed after birth to separate conjoined twins. The complexity of the operation depends in part on where the twins are joined and how many organs they share.