Black-White disparities in maternal vulnerability and adverse pregnancy outcomes: an ecological population study in the United States, 2014-2018.

Background: Systematic information on the association between community-level determinants and maternal health outcomes and disparities is needed. We aimed to investigate multi-dimensional place-based contributions to Black-White maternal health disparities in the United States. Methods: We constructed the Maternal Vulnerability Index, a geospatial measure of vulnerability to poor maternal health. The index was linked to 13m live births and maternal deaths to mothers aged 10-44 for 2014-2018 in the United States. We quantified racial disparities in exposure to higher risk environments, and used logistic regression to estimate associations between race, vulnerability, and maternal death (n = 3633), low birthweight (n = 1.1m), and preterm birth (n = 1.3m). Findings: Black mothers lived in disproportionately higher maternal vulnerability counties, when compared to White mothers (median of 55 vs 36/100 points). Giving birth in the highest-quartile MVI counties was associated with an increase in the odds of poor outcomes when compared to the lowest-quartile (aOR 1.43 [95% CI 1.20-1.71] for mortality, 1.39 [1.37-1.41] for low birthweight and 1.41 [1.39-1.43] for preterm birth, adjusted for age, educational attainment level and race/ethnicity). Racial disparities exist in low- and high-vulnerability counties: Black mothers in the least vulnerable counties remain at higher risk of maternal mortality, preterm birth, and low birthweight as White mothers in the most vulnerable. Interpretation: Exposure to community maternal vulnerability is associated with increased odds of adverse outcomes, but the Black-White gap in outcomes remained under all vulnerability levels. Our findings suggest that locally-informed precision health interventions and further research into racism are needed to achieve maternal health equity. Funding: Bill & Melinda Gates Foundation (grant number INV-024583).