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Causes of Stillbirths Differ by Race/Ethnicity


 

Major Finding: For white women, 91% of stillbirths occurred antepartum and only 9% were intrapartum, in contrast to black women, for whom 67% were antepartum and 33% were intrapartum.

Data Source: Population-based, case-control study of 512 stillbirths by the Stillbirth Collaborative Research Network.

Disclosures: The study was funded by the National Institute of Child Health and Human Development. Dr. Silver disclosed no conflicts of interest.

CHICAGO — Black women are more likely than white women to have stillbirths that are intrapartum and due to obstetric complications and infections, according to an analysis of 512 stillbirths by the Stillbirth Collaborative Research Network.

“The proportion of stillbirths due to various causes differs by race/ethnicity and may contribute to racial disparity in stillbirth,” Dr. Robert M. Silver said at the annual meeting of the Society for Maternal-Fetal Medicine.

Roughly 26,000 stillbirths occur each year in the United States, according to the National Center for Health Statistics (2005 data).

Non-Hispanic blacks have the highest stillbirth rate at 11.1/1,000 live births, compared with the national stillbirth rate of 6.2/1,000 live births in 2005, he noted.

The current analysis was based on all stillbirths and a representative sample of live births occurring from March 2006 to August 2008 in five geographically diverse regions in 59 hospitals.

Of the 958 eligible stillbirths, 512 had complete postmortem examinations. Roughly 36% of women were white; 22.5%, black; 34.5%, Hispanic; and 7%, other.

For white women, 91% of stillbirths occurred antepartum, and only 9% were intrapartum.

This is in contrast to black women, for whom 67% of stillbirths were antepartum and 33% were intrapartum, Dr. Silver reported on behalf of the Stillbirth Collaborative Research Network of the National Institute of Child Health and Human Development.

The investigators were able to identify a probable cause of death in 61% of stillbirths and a possible or probable cause in 81%. Forty percent of cases had more than one possible or probable cause.

The most common cause of stillbirth, occurring in 35% of cases, was placental abnormality due most often to thrombosis, infarction, or placental insufficiency.

Another 29% of cases were associated with an obstetric complication. Of these, half or 15% of the entire cohort were due to a sequence involving cervical insufficiency, preterm labor, and chorioamnionitis, said Dr. Silver, chief of maternal-fetal medicine at the University of Utah in Salt Lake City.

Other stillbirth causes included fetal abnormalities (15%), infection (13%), maternal medical conditions (10.5%), cord abnormalities (10%), and hypertension (9%).

Infection and obstetric complications were more common in intrapartum cases, while placental insufficiency was more frequent in antepartum stillbirth, he said.

Infection occurred in 10% of antepartum vs. 25% of intrapartum stillbirths; obstetric complications, in 15% of antepartum and 100% of intrapartum stillbirths; and placental causes in 39% vs. 19.5%.

Overall, more than one-third of women had stillbirths between 20 and 24 weeks' gestation.

Of note, 78% of intrapartum stillbirths occurred at weeks 20-24, almost exclusively in cases where there was no obstetric intervention for fetal indications due to a previable or periviable gestation.

“Future research should focus on placental and obstetric causes of [stillbirth] and racial disparity in stillbirth,” said Dr. Silver, who described the analysis as the “first scratch of a very large data set.”

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