Racial Disparity in Stillbirth Among Singleton, Twin, and Triplet Gestations in the United States

Abstract

We investigated the relationship between maternal race and stillbirth among singletons, twins, and triplets. We conducted a retrospective cohort study on 14,348,318 singletons, 387,419 twins, and 20,953 triplets delivered in the United States from 1995 through 1998. We compared the risk of stillbirth between pregnancies of black and those of white mothers using the generalized estimating equations framework to adjust for intracluster correlation in multiples. The proportion of black infants was 16%, 18%, and 8% among singletons, twins, and triplets, respectively. Crude stillbirth rate among singletons was 6.6 per 1,000 and 3.5 per 1,000 for black and white fetuses, respectively. Among twins, 796 stillbirths (11.6 per 1,000) were recorded for black mothers versus 3,209 stillbirths (10.1 per 1,000) among white mothers, whereas among triplets there were 233 stillbirths, of which 39 stillbirths were black fetuses (24.6 per 1,000) and 194 stillbirths were white fetuses (10.0 per 1,000). Black singletons, twins, and triplets weighed 278 g, 186 g, and 216 g less than white fetuses, respectively (P <.001). Risk of stillbirth was elevated in black fetuses compared with white fetuses among singletons (adjusted odds ratio [OR] 2.9, 95% confidence interval [CI] 2.8-3.0) and twins (OR 1.3. 95% CI 1.2-1.4) but comparable among triplets (OR 1.2, 95% CI 0.7-2.1). This decreasing trend was significant (P for trend <.001). The disparity of stillbirths between black and white fetuses still persists among singletons and twins. Among triplet gestations, however, the 2 racial groups have a comparable risk level. Our findings highlight the need for a rigorous research agenda to elucidate causes of stillbirth across racial/ethnic entities in the United States. II-2