Racial and Ethnic Disparities in Primary Cesarean Birth and Adverse Outcomes Among Low-Risk Nulliparous People.

OBJECTIVE: To compare trend of primary cesarean delivery rate and composite neonatal and maternal adverse outcomes in low-risk pregnancies among racial and ethnic groups: non-Hispanic White, non-Hispanic Black, and Hispanic. METHODS: This population-based cohort study used U.S. vital statistics data (2015-2019) to evaluate low-risk, nulliparous patients with nonanomalous singletons who labored and delivered at 37-41 weeks of gestation. The primary outcome was the primary cesarean delivery rate. Secondary outcomes included composite neonatal adverse outcome (Apgar score less than 5 at 5 minutes, assisted ventilation for more than 6 hours, seizure, or death), and composite maternal adverse outcome (intensive care unit admission, blood transfusion, uterine rupture, or unplanned hysterectomy), as well as infant death. Multivariable Poisson regression models were used to estimate adjusted relative risks (aRR) and 95% CIs. RESULTS: Among 4.3 million births, 60.6% identified as non-Hispanic White, 14.6% identified as non-Hispanic Black, and 24.8% identified as Hispanic. The rate of primary cesarean delivery was 18.5% (n=804,155). An increased risk for cesarean delivery was found in non-Hispanic Black (21.7%, aRR 1.24, 95% CI 1.23-1.25) and Hispanic (17.3%, aRR 1.09, 95% CI 1.09-1.10) individuals, compared with non-Hispanic White individuals (18.1%) after multivariable adjustment. There was an upward trend in the rate of primary cesarean delivery in all racial and ethnic groups ( P for linear trend<0.001 for all groups). However, the racial and ethnic disparity in the rate of primary cesarean delivery remained stable during the study period. The composite neonatal adverse outcome was lower in Hispanic individuals in all newborns (10.7 vs 8.3 per 1,000 live births, aRR 0.74, 95% CI 0.72-0.75), and in newborns delivered by primary cesarean delivery (18.5 vs 15.0 per 1,000 live births, aRR 0.73, 95% CI 0.70-0.76), compared with non-Hispanic White individuals. CONCLUSION: Using a nationally representative sample in the United States, we found racial and ethnic disparities in the primary cesarean delivery rate in low-risk nulliparous patients, which persisted throughout the study period.