Association of Medicaid Expansion Under the Affordable Care Act With Medicaid Coverage in the Prepregnancy, Prenatal, and Postpartum Periods.

Introduction: We evaluated how the Affordable Care Act (ACA) Medicaid eligibility expansion affected perinatal insurance coverage patterns for Medicaid-enrolled beneficiaries who gave birth overall and by race/ethnicity. We also examined state-level heterogeneous impacts.

Methods: Using the 2011-2013 Medicaid Analytic eXtract and the 2016-2018 Transformed Medicaid Statistical Information System Analytic File databases, we identified 1.4 million beneficiaries giving birth in 2012 (pre-ACA expansion cohort) and 1.5 million in 2017 (post-ACA expansion cohort). We constructed monthly coverage rates for the two cohorts by state Medicaid expansion status and obtained difference-in-differences estimates of the association of Medicaid expansion with coverage overall and by race/ethnicity group (non-Hispanic White, non-Hispanic Black, and Hispanic). To explore state-level heterogeneous impacts, we divided the expansion and non-expansion states into groups based on the differences in the income eligibility limits for low-income parents in each state between 2012 and 2017.

Results: Medicaid expansion was associated with 13 percentage points higher coverage in the 9 to 12 months before giving birth, and 11 percentage points higher coverage at 6 to 12 months postpartum. Hispanic birthing individuals had the greatest relative increases in coverage, followed by non-Hispanic White and non-Hispanic Black individuals. In Medicaid expansion states, those who experienced the greatest increases in income eligibility limits for low-income parents generally saw the greatest increases in coverage. In non-expansion states, there was less heterogeneity between state groupings.

Conclusions: Pregnancy-related Medicaid eligibility did not have major changes in the 2010s. However, states' adoption of ACA Medicaid expansion after 2012 was associated with increased Medicaid coverage before, during, and after pregnancy. The increases varied by race/ethnicity and across states.