Adverse Maternal Outcome Disparities in a Clinically Low-risk Cohort

Abstract Maternal health in the United States is characterized by persistent racial and ethnic disparities, even among clinically low-risk patients. Health systems often report outcomes in aggregate, a practice that can obscure inequities. We examined adverse maternal outcomes (AMO) among clinically low-risk patients stratified by race/ethnicity and assessed whether area-level social vulnerability differed across geographic patterns of AMO. We conducted a secondary analysis of 7,691 patients who received intrapartum care from certified nurse-midwives or obstetricians at a tertiary academic hospital between 2013 and 2018. We evaluated severe maternal morbidity (SMM), adapted from CDC criteria, and AMO which included SMM plus postpartum hemorrhage, intra-amniotic infection, obstetric anal sphincter injury, and unplanned cesarean delivery. We stratified outcomes by mutually exclusive, census-derived racial/ethnic categories based on patient self-report. We used chi-squared, Student's t-tests, and one-way ANOVA for comparisons, and logistic regression to assess AMO by racial/ethnic category. We used the Mann-Whitney U test to compare area-level social vulnerability indicators between zip codes with the highest and lowest AMO prevalence, and Geographic Information Systems (GIS) to map the zip code distribution. AMO, but not SMM, differed by racial/ethnic category. Patients identifying as non-Hispanic Asian had the highest AMO (38%) and more than twice the odds compared with non-Hispanic White patients (aOR: 2.02; 95% CI: 1.63–2.51; p < 0.001). Zip code–level social vulnerability indicators did not differ by AMO prevalence. Racial and ethnic disparities in AMO persisted in a clinically low-risk cohort, underscoring the importance of disaggregated reporting to identify inequities that may be masked in aggregate analyses.