Objective: We examine the association between prior cesarean delivery and risk of stillbirth in a subsequent pregnancy.
Methods: The Missouri maternally linked cohort data set containing births from 1978 through 1997 was used. We identified a cohort of women who delivered live births by cesarean delivery and a comparison cohort of women who delivered live births vaginally in their first pregnancies. We then compared the risks of stillbirth in the second pregnancy between the 2 groups.
Results: We analyzed 396,441 women with information on first and second pregnancies, comprising 71,950 (18.1%) in the cesarean arm, and 324,491 (81.9%) in the vaginal birth arm. Rates of stillbirth among women with and those without history of cesarean delivery were 4.4 and 4.1 per 1,000 births, respectively (P = .2). The adjusted estimates also showed no difference in risk for stillbirth between the 2 groups (odds ratio [OR] 1.1, 95% confidence interval [CI] 1.0-1.3). Among whites, the stillbirth rates in women with and those without history of cesarean delivery were 3.7 and 3.6 per 1,000 births, respectively (OR 1.0, 95% CI 0.9-1.2). Among blacks, both the absolute and the adjusted relative risks for stillbirth were elevated in mothers with history of cesarean delivery (stillbirth rate 9.3 versus 6.8 per 1,000 births; OR 1.4, 95% CI 1.1-1.7).
Conclusion: Overall, our analysis did not detect an association between cesarean history and subsequent stillbirth. However, cesarean delivery may increase the risk for subsequent stillbirth among black mothers, a group with the highest cesarean delivery rate in the country.
Level of evidence: III.