The Effects of ACA-Medicaid Expansion on Maternal and Infant Health Outcomes in the American South

Maternal and infant health outcomes in the American South lag behind those in other U.S. regions. This study estimates the causal impact of Medicaid expansion to 138 percent of the Federal Poverty Level on maternal and infant health outcomes, using county-level data from the National Vital Statistics System (2010--2017). We employ a difference-in-differences design, comparing counties in expansion and non-expansion states, and use inverse propensity score weighting to improve covariate balance. To flexibly adjust for baseline differences, we extend the analysis with a machine learning–based Doubly Robust DiD estimator. Our findings show that Medicaid expansion significantly reduced pregnancy-associated mortality among non-Hispanic Black mothers, primarily by lowering pregnancy-related deaths, with no effect on incidental causes. No significant impact is found for non-Hispanic White mothers. While infant mortality rates remained unchanged for both groups, the expansion modestly improved birthweight outcomes among Black infants. These results highlight the potential of Medicaid expansion to reduce racial disparities in maternal and infant health in the American South.