Trends in cesarean delivery at preterm gestation and association with perinatal mortality

Objective: We sought to examine the extent to which a temporal increase in preterm cesarean delivery is associated with gestational agespecific changes in perinatal survival in preterm gestations. Study Design: We utilized data on singleton births in the United States (1990 through 2004) delivered between 24-36 weeks' gestation. Associations between changes in cesarean delivery at preterm gestations and trends in the risk of preterm stillbirth, and neonatal and perinatal mortality were estimated before and after adjustments for a variety of potential confounders. Results: From 1990 through 2004, cesarean delivery rates increased by 50.6%, 40.7%, and 35.8% at 24-27, 28-33, and 34-36 weeks, respectively. The largest incremental effect of cesarean was associated with a reduction in stillbirths by 5.8%, 14.2%, and 23.1% at 24-27, 28-33, and 34-36 weeks, respectively, leading to an 11.4%, 4.9%, and 0.6% reduction in perinatal deaths at 24-27, 28-33, and 34-36 weeks, respectively. Conclusion: Increasing rates of preterm cesarean were associated with improved perinatal survival. This association was evident largely because of dramatic incremental declines in stillbirths.