Williams Manual of Pregnancy Complications, 23 ed.

CHAPTER 94. Stillbirth

The stillbirth rate for birth weights of 500 g or greater has decreased significantly over recent decades. Along with the decline in stillbirth rate, the pattern of causes of stillbirths has changed appreciably. With advances in obstetrics, clinical genetics, maternal–fetal and neonatal medicine, and perinatal pathology, an increasing number of stillbirths that had previously been categorized as “unexplained” are now attributed to specific causes. Such information can improve management of subsequent pregnancies.

The more common recognized causes of fetal death include infection, malformations, fetal growth restriction, and abruptio placentae. However, more than a fourth of all fetal deaths remain unexplained.

CAUSES OF FETAL DEATH

It is recognized that an autopsy performed by a pathologist with expertise in fetal and placental disorders, assisted by a team including maternal–fetal medicine, genetics, and pediatric specialists, can often determine the cause of stillbirth. Explanations for fetal death can be broadly categorized as fetal, placental, or maternal in origin. Some causes of fetal death are shown in Table 94-1.

TABLE 94-1. Categories and Causes of Fetal Death

image

image

image

Fetal Causes

Between 25 and 40 percent of stillbirths have fetal causes and these include congenital anomalies, infection, malnutrition, nonimmune hydrops, and anti-D isoimmunization.

The reported incidence of major congenital malformations in stillborns is highly variable, and depends on whether an autopsy was performed. Approximately one-third of fetal deaths are caused by structural anomalies, of which neural-tube defects, hydrops, isolated hydrocephalus, and complex congenital heart disease are the most common. These structural anomalies and aneuploidy are particularly amenable to antenatal diagnosis.

The incidence of stillbirths caused by fetal infection appears to be remarkably consistent. Six percent of stillbirths are attributed to infection. Most are diagnosed as “chorioamnionitis,” and some as “fetal or intrauterine sepsis.” Congenital syphilis is a more common cause of fetal death in indigent and inner-city women. Other potentially lethal infections include cytomegalovirus, parvovirus B19, rubella, varicella, and listeriosis.

Placental Causes

Approximately 15 to 25 percent of fetal deaths are attributed to problems of the placenta, membranes, or cord. Placental abruption (see Chapter 25) is the most common single identifiable cause of fetal death.

Clinically significant placental and membrane infection rarely occurs in the absence of significant fetal infection. Some exceptions are tuberculosis and malaria. Microscopic examination of the placenta and membranes may help identify an infectious cause. Chorioamnionitis is characterized by infiltration of the chorion by mononuclear and polymorphonuclear leukocytes. These findings, however, are nonspecific.

Placental infarcts show fibrinoid trophoblastic degeneration, calcification, and ischemic infarction from spiral artery occlusion. When there is severe hypertension, two-thirds of placentas reveal such infarcts.

Fetal–maternal hemorrhage (see Chapter 27) can be of such severity as to induce fetal death. Life-threatening fetal–maternal hemorrhage is associated with severe maternal trauma.

Twin-to-twin transfusion is a common placental cause of fetal death in monochorionic multifetal pregnancies (see Chapter 41).

Maternal Causes

Perhaps surprisingly, maternal disorders make only a small contribution to stillbirths. Hypertensive disorders and diabetes are the two most commonly cited maternal diseases associated with stillborn infants (5 to 8 percent of stillbirths). Lupus anticoagulant and anticardiolipin antibodies (see Chapter 54) are associated with decidual vasculopathy, placental infarction, fetal growth restriction, recurrent abortion, and fetal death. Recently, hereditary thrombophilias (see Chapter 53) have been associated with placental abruption, fetal growth restriction, and stillbirths.

Unexplained Stillbirths

With careful assessment of the clinical course, meticulous examination of the fresh stillborn, and appropriate laboratory investigations, including autopsy, as few as 10 percent of fetal deaths may remain unclassified. The difficulty of assessing the cause of fetal death is magnified in preterm infants.

EVALUATION OF THE STILLBORN INFANT

It is important to try to determine the cause of each stillbirth. First, the mother’s psychological adaptation to a significant loss may be eased by knowledge of a specific cause. Second, it may help to assuage the guilt that is part of grieving. Importantly, appropriate diagnosis makes counseling regarding recurrence more accurate and may allow intervention to prevent a similar outcome in the next pregnancy.

Clinical Examination

A thorough examination of the stillborn infant, placenta, and membranes should be performed at delivery. The checklist used at Parkland Hospital is outlined in Table 94-2.

TABLE 94-2. Protocol for Examination of Stillborns

image

image

Genetic Evaluation

If autopsy and chromosomal studies are performed when indicated, up to 35 percent of stillborn infants are discovered to have congenital structural anomalies. The American College of Obstetricians and Gynecologists (2009) recommends ideally karyotyping all stillborns. In the absence of structural malformations, up to 5 percent of stillborns will have a chromosomal abnormality. Chromosomal information is particularly valuable in infants with dysmorphic features, anomalies, hydrops, or growth restriction. Fetal karoyotype is also important if a parent is a carrier for a balanced translocation, or a mosaic chromosomal pattern.

Autopsy

Patients should be counseled that a full autopsy, including photography, radiography, and bacterial cultures, with selective use of procedures such as chromosomal and histopathological studies can often determine the cause of death.

PSYCHOLOGICAL ASPECTS

Fetal death is a psychologically traumatic event for a woman and her family. The woman experiencing a stillbirth is at increased risk for postpartum depression for up to 6 months (see Chapter 80). Women should be given sufficient time with the stillborn infant after delivery along with a token of remembrance in order to ease anxiety.

MANAGEMENT OF WOMEN WITH A PREVIOUS STILLBIRTH

A woman with a prior stillbirth has long been accepted to be at increased risk for adverse outcomes in subsequent pregnancies. Fortunately, however, there are very few conditions actually associated with recurrent stillbirth. Other than hereditary disorders, only maternal conditions such as diabetes, chronic hypertension, or hereditary thrombophilia increase the risk of recurrence. Nonetheless, women with confirmed prior fetal deaths are generally offered delivery during a subsequent pregnancy when fetal maturity is ensured. The benefit of antepartum fetal heart rate testing in these women has not been clearly demonstrated. The American College of Obstetricians and Gynecologists (2009) recommends that antepartum surveillance should begin at 32 weeks or later in an otherwise healthy woman with a history of stillbirth.


For further reading in Williams Obstetrics, 23rd ed.,

see Chapter 29, “Diseases and Injuries of the Fetus and Newborn.”


APPENDICES

image