Infant and Neonatal Mortality for Primary Cesarean and Vaginal Births to Women with “No Indicated Risk,” United States, 1998–2001 Birth Cohorts

TLDR

Cesarean section rates in the United States have risen sharply, even among women at low risk for the procedure. This study investigates infant and neonatal mortality risks associated with primary cesarean versus vaginal delivery in singleton full‑term pregnancies without medical indications, emphasizing the widespread mortality differential. Using linked birth and infant death data from 1998‑2001 (5.76 million live births) and multivariable logistic regression, the authors modeled neonatal survival probabilities by delivery method and risk factors. Neonatal mortality was higher after cesarean (1.77 / 1,000) than vaginal (0.62 / 1,000), and the excess persisted after adjustment, remaining widespread across causes of death.

Abstract

The percentage of United States' births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full-term (37-41 weeks' gestation) women with no indicated medical risks or complications.National linked birth and infant death data for the 1998-2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors.Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death.Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication.