Medicaid Coverage and Postpartum Opioid Use Disorder Treatment

Opioid use disorder (OUD) among pregnant women in the United States has risen more than fourfold since 1999, making substance use a leading cause of maternal mortality. Medicaid finances the majority of births and substance use disorder treatment in the U.S., yet until recently, coverage typically ends 60 days postpartum, potentially disrupting care continuity. The American Rescue Plan of 2021 extends postpartum Medicaid coverage from two months to 12 months, creating a natural experiment to evaluate the impact of coverage on access to medications for OUD (MOUD), the gold-standard treatment. We use linked nationwide all-payer medical and retail pharmacy claims from IQVIA in a difference-in-differences framework comparing postpartum MOUD continuity between Medicaid- and commercially-insured parents with a prenatal history of MOUD use. Extended Medicaid postpartum coverage increases Medicaid-financed MOUD months by 8.55%, the likelihood of continuing MOUD beyond 60 days by 5.12%, and total MOUD supply days by 7.99%. These gains are slightly offset by other payer reductions, yet result in a net 5.10% increase in overall MOUD months and 4.64% rise in treatment adherence. Findings highlight the importance of coverage duration as a practical lever to sustain MOUD treatment in the crucial first year after delivery period.