Investigating racial differences in risk factors for primary cesarean delivery.

Abstract

The objective of the study was to investigate differences in sociodemographic, medical, and obstetric risk factors for primary cesarean delivery between black and white women. We conducted a retrospective cohort study among 25,251 black and white women delivering a live, singleton infant with vertex presentation at a large, regional hospital between 2004 and 2010. Demographic and clinical data were derived from electronic hospital records. Differences in risk factors for primary cesarean delivery were analyzed using a modified Poisson regression approach stratified by race and parity. Black and white women had a primary cesarean delivery rate of 24.7% and 22.2%, respectively (P < .001). Black women had an increased risk of cesarean delivery after adjusting for sociodemographic and clinical risk factors (adjusted relative risk [RR], 1.23; 95% confidence interval [CI], 1.17-1.29). Among nulliparas, labor induction had a greater effect on cesarean delivery for black women (adjusted RR, 1.32; 95% CI, 1.20-1.44) than for white women (adjusted RR, 1.13; 95% CI, 1.07-1.20). Among multiparas, labor induction reduced the risk of cesarean delivery for white women (adjusted RR, 0.63; 95% CI, 0.55-0.72), whereas no association was observed for black women (adjusted RR, 1.08; 95% CI, 0.92-1.28). Advanced maternal age was a stronger risk factor for black women (adjusted RR, 1.72; 95% CI, 1.43-2.08) than for white women (adjusted RR, 1.30; 95% CI, 1.11-1.52) among multiparas only. Among nulliparas, delivery at 37-38 weeks' gestation reduced the risk of cesarean delivery for black women (adjusted RR, 0.82; 95% CI, 0.73-0.92), whereas no association was observed for white women (adjusted RR, 0.96; 95% CI, 0.90-1.04). Labor induction, among nulliparous women, and advanced maternal age, among multiparous women, are stronger risk factors for primary cesarean delivery for black women than for white women.