A Not entirely, although the main causes have been identified: intrauterine growth restriction, malformations, infection, and “unexplained” abruption. Black women are twice as likely to experience stillbirth as women of other races.
Stillbirth is the cause of about half of all perinatal deaths in the United States (6.4 per 1,000 births). In the past 50 years, the stillbirth rate has decreased about 4-fold, but is still roughly 10 times more than the rate for sudden infant death. The World Health Organization defines stillbirth as fetal loss in pregnancy beyond 20 weeks.
Cause depends on gestational age
Over the past 4 decades, the causes of stillbirth have shifted away from Rh disease and intrapartum loss and toward “unexplained” abruption, intrauterine growth restriction, malformations, and infection.
Categorizing stillbirths by gestational age gives a different rank order of causes. For early stillbirths (24–27 weeks), leading causes are infection (19%), abruption (14%), and anomalies (14%). For late stillbirths (≥28 weeks), the leading causes are “unexplained” (26%–40%, depending on gestational age), fetal malformations (14%–19%), and abruption (12%–18%).
Common risk factors
- Black race—the risk doubles even with adequate prenatal care
- Advanced maternal age, even after accounting for medical conditions
- Obesity, even after controlling for gestational diabetes and hypertension
- Thrombophilia—odds ratios range from 1.8 to 12
- Infection and “immunologic exposure,” including parvovirus B19, toxoplasmosis, and listeriosis
- Advanced reproductive technology, even among singletons
- Multiple gestation
- Medical diseases, particularly systemic lupus erythematosus
Fretts proposes these practices:
- Encourage smoking cessation.
- Assess risk factors, including screening for and treatment of diabetes and hypertension, and screening for congenital anomalies and intrauterine growth restriction.
- Consider obese women and women older than 35 years at higher risk.
- Because many stillbirths occur in women with no apparent risk factors, screen even low-risk patients with fetal kick counting in late pregnancy.
- Be vigorous in screening for and management of pregnancies affected by intrauterine growth restriction.
- Use a liberal antepartum testing strategy even in women at moderately increased risk (such as age >35 years).
- When stillbirth occurs, perform “appropriate and comprehensive stillbirth assessment,” most importantly an autopsy. Other tests to use selectively: fetal fasting glucose, hemoglobin A1C, Kleihauer-Betke, urine toxicology, and thrombophilia evaluation. “TORCH titers” to detect infection almost never further diagnosis if there are no findings from autopsy or the placenta.
- Induce labor within 24 hours of fetal death, to decrease maternal anxiety.