Causes of Death Among Stillbirths

Abstract

The stillbirth rate in the United States is higher than that of other developed countries. Since 2003, the rate has stagnated at 6.2 stillbirths per 1000 births. There is a lack of information on causes of stillbirth. Strategies to reduce the stillbirth rate will require systematic investigation into the cause of death. The stillbirth rate among non-Hispanic black women is 2.3-fold higher than that of non-Hispanic white women. This racial disparity is largely unexplained. This multicenter population-based case-control study determined the causes of death among stillbirths and stratified the causes according to race/ethnicity. All stillbirths that occurred at 20 weeks or later between 2006 and 2008 were examined in data from 59 tertiary care and community hospitals that had access to at least 90% of the stillbirth and live birth deliveries in 5 catchment areas defined by state and county boundaries. Data on deliveries resulting from termination of a live fetus were excluded. Several outcome measures were evaluated to systematically assign causes of death. Standardized perinatal postmortem examination and placental pathology evaluation were performed at delivery. Other outcome measures included medical history, karyotype, and other laboratory tests. Of the 663 women with stillbirth enrolled, 500 (75.4%) allowed a complete postmortem examination of their 512 stillborn neonates. Among the stillbirths, a probable cause of death was found for 312 cases (60.9%; 95% confidence interval [CI], 56.5%-65.2%) and possible or probable cause for 390 (76.2%; 95% CI, 72.2%-79.8%). The most common causes of death were the following: obstetric complications (29.3%; 95% CI, 25.4%-33.5%), placental abnormalities (23.6%; 95% CI, 20.1%-27.6%), fetal genetic/structural abnormalities (13.7%; 95% CI, 10.9%-17.0%), infection (12.9%; 95% CI, 10.2%-16.2%), umbilical cord abnormalities (10.4%; 95% CI, 7.9%-13.4%), hypertensive disorders (9.2%; 95% CI, 6.9%-12.1%), and other maternal medical complications (7.8%; 95% CI, 5.7%-10.6%). Compared with non-Hispanic white women and all Hispanics, non-Hispanic black women had a higher proportion of stillbirths associated with obstetric complications (43.5% vs. 23.7%; difference: 19.8%; 95% CI, 9.7%-29.9%; P < 0.001) and infections (25.2% vs. 7.8%; difference: 17.4%; 95% CI, 9.0%-25.8%; P < 0.001). Intrapartum and early in gestation stillbirths were more common among non-Hispanic black women. The most likely sources contributing to identifying a probable or possible cause of death were placental histology (52.3%; 95% CI, 47.9%-56.7%), perinatal postmortem examination (31.4%; 95% CI, 27.5%-35.7%), and karyotype (9%; 95% CI, 6.3%-12.5%). These findings show that a systematic and thorough evaluation of a population-based cohort led to a probable or possible cause of death for the majority of cases of stillbirth. Causes were differentially distributed by race/ethnicity