Labor and delivery unit practices and racial and ethnic disparities in severe maternal and neonatal morbidity among nulliparous individuals with low-risk pregnancies.

Persistent racial and ethnic disparities exist in severe maternal and neonatal morbidity, which may be due in part to differences in labor and delivery unit practices across hospitals. We used data collected from 184 hospitals in California (2015-2018) to assess whether nulliparous individuals with low-risk pregnancies differ by race and ethnicity in giving birth at hospitals that tend to use lower-interventional labor and delivery unit practices, and whether such differences contribute to disparities in severe maternal and neonatal morbidity. We classified labor and delivery units as higher- or lower-interventional based on a latent class analysis of survey responses about the frequency of using lower-interventional practices. We used a modified doubly robust g-estimator to estimate counterfactual disparity measures, setting all hospitals to be lower-interventional. Among 348,990 low-risk livebirths, the proportion occurring at lower-interventional hospitals was lowest in Black and Latino individuals (17% and 16%, respectively) and highest in American Indian and Alaska Native (AI/AN) and White individuals (29% in both). Severe maternal and neonatal morbidity occurred most frequently among AI/AN individuals. Counterfactual disparity measures suggested that if all births occurred at lower-interventional hospitals, racial and ethnic disparities in the outcomes would modestly increase, except for severe neonatal morbidity among AI/AN individuals.