NEW YORK (Reuters Health) - African-American women are twice as likely to suffer a late-pregnancy loss as white women -- partly because of higher rates of pregnancy- and labor-related complications, a government study finds.
Researchers at the U.S. National Institutes of Health found that among more than 5 million pregnancies in 2001 and 2002, black women were more likely than white or Hispanic women to have a stillbirth.
Among African Americans, 22 of every 1,000 pregnancies ended in a stillbirth. That compared with 10 and 10.5 per 1,000 among white and Hispanic women, respectively.
Health conditions like high blood pressure and diabetes and certain complications during pregnancy -- such as uterine bleeding and premature rupture of the sac surrounding the fetus -- explained a larger share of black women's stillbirth risk compared with white and Hispanic women.
The same was true of labor-related conditions, including problems with the placenta or umbilical cord.
Those disparities suggest that improvements in black women's health before and during early pregnancy could help erase some of the gap in stillbirth risk, the researchers report in the American Journal of Obstetrics & Gynecology.
Stillbirth refers to fetal deaths that occur after the 20th week of pregnancy. Among the most common causes are birth defects, poor fetal growth and problems with the placenta -- such as placental abruption, where the placenta peels away from the wall of the uterus, leading to heavy bleeding.
Past studies have found that African-American women are at increased risk of stillbirth, and while the national rate of stillbirth has declined in the past 20 years, the racial gap has not narrowed.
These latest findings shed more light on the problem, according to the researchers, led by Dr. Marian Willinger of the National Institute of Child Health and Human Development.
Using records on more than 5.1 million U.S. pregnancies, the researchers found that racial disparities in stillbirth risk were greatest in the 20th to 23rd week of pregnancy and smallest in the last few weeks.
Underlying medical conditions and pregnancy- and labor-related complications accounted for 30 percent of the risk among black women, compared with 20 percent among white and Hispanic women.
In contrast, birth defects and poor fetal growth were bigger factors in white women's stillbirth risk than they were for black women.
A "striking" finding, according to the researchers, is that the racial disparity was even more pronounced among more-educated women. That was because higher education (beyond high school) was linked to a 30 percent reduction in stillbirth risk among white women, while there was little evidence of benefit among black women.
Higher education -- often a marker of advantages like higher income and better healthcare -- is generally associated with better pregnancy outcomes. Exactly why better-educated black women failed to show a substantial decrease in stillbirth risk is unclear.
More research is needed, Willinger's team writes, to see whether biological mechanisms may be contributing to the racial disparity.
SOURCE: American Journal of Obstetrics & Gynecology, November 2009.