Racial disparities in U.S. women’s risk of experiencing a stillbirth are greatest before 37 weeks’ gestation and are associated with maternal education and maternal and fetal conditions.1 According to an analysis of data on more than five million pregnancies from 2001 and 2002, black women’s cumulative risk of having a stillbirth—defined as a fetal death occurring at or after 20 weeks of gestation—was twice that of white women (relative risk, 2.2); the disparity in stillbirth risk between blacks and whites was greatest at 20–23 weeks’ gestation (2.8). Having more than 12 years education was associated with a 30% reduction in the stillbirth risk among whites, but only a 10% reduction among blacks. Maternal health problems contributed to a greater proportion of the stillbirth risk for black women than for white women, whereas for fetal complications’ contribution to stillbirth risk, the reverse was true.

To examine racial disparity in U.S women’s risk of stillbirth across gestational age, researchers used 2001–2002 National Center for Health Statistics perinatal mortality data, and birth and infant death data from 36 states. The hazard of stillbirth by gestational age among women with a singleton pregnancy was calculated separately for three maternal racial and ethnic groups: white, black and Hispanic. In addition, the researchers calculated the race-specific hazard of stillbirth excluding data on women who had experienced certain medical or pregnancy- or labor-related conditions, as well as fetal complications, to examine the relationship of such conditions with stillbirth hazard across gestational age.

Of the 5.1 million singleton births delivered at 20–41 weeks’ gestation, 58% occurred among whites, 13% among blacks and 23% among Hispanics. The cumulative stillbirth hazard for white women was 10.0 fetal deaths per 1,000 pregnancies; the hazards for Hispanics and blacks were 10.6 and 22.1, respectively. Black women’s cumulative risk of having a stillbirth was twice that of white women (relative risk, 2.2); the disparity was greatest at 20–23 weeks (2.8) and decreased throughout preterm gestation (before 37 weeks), reaching a low at 39–40 weeks (1.6). Hispanic women’s overall risk of stillbirth was slightly higher than whites’ (1.1); the disparity between Hispanics and whites was greatest at 32–33 weeks (1.2), but was nonsignificant at most other age intervals.

In analyses by maternal characteristics, greater education was associated with a substantial reduction in white women’s risk of experiencing a stillbirth: Those who had more than 12 years of education had only 70% of the risk of those who had 12 or fewer years of schooling (relative risk, 0.7); the association, however, was not as strong among blacks (0.9) and was nonsignificant among Hispanics. The black-white disparity in stillbirth hazard was greater for women of the higher education category (2.4) than for those who had fewer years of schooling (1.8). For women of all three races, those older than 35 had higher risks than younger women of having a stillbirth (1.4–1.7), and those who had given birth before had lower risks than others (0.3–0.4).

In the analyses assessing potential maternal and fetal factors in stillbirth hazards, the researchers found that maternal conditions overall accounted for a greater proportion of the hazard for black women than for whites and Hispanics (30% vs. 19–20%). The contribution of fetal conditions was greater for whites and Hispanics than for blacks (small for gestational age, 25% each vs. 20%; congenital anomalies, 16–20% vs. 11%).

The authors conclude that “preterm gestation is a period associated with increased vulnerability for stillbirth among black compared with white pregnancies.” They suggest that more research is needed to “probe the cultural and social determinants of racial disparities in risk among blacks and Hispanics, as higher educational status appears to widen rather than reduce these disparities.”

J. Rosenberg

REFERENCE

1. Willinger M, Ko CW and Reddy UM, Racial disparities in stillbirth risk across gestation in the United States, American Journal of Obstetrics & Gynecology, 2009, 201(5):469.e1–e8.