Cesarean delivery for first pregnancy and neonatal morbidity and mortality in second pregnancy

To examine impact of cesarean delivery in first pregnancy on neonatal mortality and morbidity in second pregnancy.

Retrospective cohort study using 1995-2002 US birth registration data. Neonatal mortality and morbidity in second pregnancy of cesarean deliveries in the first pregnancy were compared with vaginal deliveries in the first pregnancy.

A total of 9,643,175 singleton second births were eligible in the analysis after excluding those with unknown delivery method (1,801,339 with a previous cesarean delivery and 7,841,836 with a previous vaginal delivery). Compared with vaginal delivery group, infants born to mothers with a previous cesarean delivery had increased risks of assisted ventilation (OR=1.47, 95% CI 1.46, 1.49), low Apgar's score (OR=1.14, 95% CI 1.12, 1.17), seizure (OR=1.36, 95% CI 1.27, 1.45), fetal distress (OR=1.46, 95% CI 1.44, 1.47), and asphyxia-related neonatal death (OR=1.40, 95% CI 1.29, 1.52). The association between mode of delivery in first pregnancy and neonatal outcomes in second pregnancy remained the same after excluding women with chronic health problems or adverse birth history and adjusting for potential confounding factors.

Cesarean delivery in first pregnancy is associated with increased risks of neonatal morbidity and mortality in second pregnancy.