PROJECT SUMMARY Pregnant women with opioid use disorder (OUD) are at high risk of potentially avoidable morbidity and mortality. Since 2000, this population has experienced large increases in maternal mortality, largely driven by rising rates of drug overdose. Use of medications for opioid use disorder (MOUD) reduces the risk of poor maternal health outcomes, but pregnant women with OUD infrequently access them. More than 80% of pregnant women with OUD are enrolled in Medicaid and eligible to access MOUD throughout pregnancy, but the structure of state Medicaid programs may deter use of these lifesaving medications. Medicaid managed care (MMC) organizations are the dominant vehicle for delivering coverage to enrollees, but often impose more restrictions to access to MOUD than Medicaid fee-for-service (FFS). Several states have implemented uniform preferred drug lists (PDL) to reduce variation in coverage between Medicaid FFS and MMC, but the impact of this policy on MOUD use is unknown. Given that FFS coverage of MOUD is often more generous, uniform PDLs may improve access to MOUD by standardizing the drugs that MMC organizations must cover to a state-wide benchmark. However, the impact of uniform PDLs on MOUD use is unknown, and no prior research has assessed the broader impact of MMC enrollment on maternal health outcomes among pregnant women with OUD. The long-term goal of this work is to identify Medicaid policies that improve the health of pregnant women with OUD. In pursuit of this goal, the specific aims of this proposal are to: (1) Evaluate differences in MOUD use and severe maternal morbidity among pregnant women with OUD enrolled in Medicaid FFS vs. MMC, and if there are any differences in these outcomes by race/ethnicity (2) Determine if MOUD use changes after adoption of uniform PDLs between Medicaid FFS and MMC, and (3) Assess if MMC enrollment increases the rate of severe maternal morbidity among pregnant women with OUD compared to FFS enrollment. Building on the findings from Aim 1, a study examining the national association of MMC with aforementioned outcomes, we will employ quasi-experimental approaches in Aims 2-3 to examine the impact of MMC on MOUD use and severe maternal morbidity in states exposed to temporal and geographic policy variation. This work is innovative because it uses national Medicaid claims data to examine MOUD use and severe maternal morbidity, which is more reliable than survey data and more comprehensive than claims from a single state. This proposal is significant because it focuses on how MMC may adversely impact the health of pregnant women with OUD, which has not been considered by prior research. This proposal responds to the Special Emphasis Notice focused on the substance use disorder crisis in the United States (SEN NOT-HS-21-010). This research will identify the effects of MMC enrollment and policies on MOUD use and severe maternal morbidity among pregnant women with OUD, which may provide eviden...