Medicaid Expansion and Severe Maternal Morbidity During Delivery Hospitalizations

OBJECTIVE: To examine the association between the Affordable Care Act (ACA) Medicaid expansion and severe maternal morbidity (SMM) during delivery hospitalization. METHODS: This was a retrospective, repeated cross-sectional study using data from the Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. All delivery hospitalizations from 2010 to 2018 were analyzed; of the 26 U.S. states included, 16 expanded Medicaid in January 2014 and 10 did not. The primary outcome was the SMM rate, as defined by Centers for Disease Control and Prevention criteria, exclusive of blood transfusion. We used a quasi-experimental design to compare changes in the SMM rate from preexpansion (2010-2013) to postexpansion (2015-2018) in states that expanded Medicaid compared with those that did not. Generalized synthetic control models were used to estimate the adjusted average treatment effect on the treated. RESULTS: The study sample included 11.98 million delivery hospitalizations; among those hospitalized, 82,903 (69.2/10,000) experienced SMM. The ACA Medicaid expansion was associated with a 5.2% (95% CI, 2.1-8.2) increase in the proportion of delivery hospitalizations paid for by Medicaid, but not with any statistically significant change in the SMM rate (0.02%; 95% CI, -0.01 to 0.04). Results were consistent in the subgroup analyses by maternal race and ethnicity and in sensitivity analyses. CONCLUSION: Expanded access to public health insurance was not associated with a reduction in SMM during delivery hospitalizations. Additional clinical and policy interventions may be required to improve maternal health outcomes.