AbstractIntroductionEvidence-based enhanced prenatal/postnatal care (EPC) programs for Medicaid-insured women have significant positive effects on care and health outcomes. However, EPC enrollment rates are typically low, enrolling less than 30% of eligible women. This study investigated the effects of a population-based systems approach on timely EPC participation and other health care utilization.MethodsThis quasi-experimental, population-based, difference-in-difference study used linked birth certificates, Medicaid claims, and EPC data from complete statewide Medicaid birth cohorts retrieved from 2009-2017 and analyzed in 2019-20. System strategies included cross-agency leadership, clinical-community linked practices, Community Health Worker care, mental health coordination, and patient empowerment. Outcomes included EPC participation and early enrollment, prenatal care adequacy, emergency department contact, and postpartum care.ResultsPrenatal EPC (7.4 absolute percentage points; 95% CI: 6.3—8.5) and first trimester EPC, (12.4; 95% CI: 10.2—14.5) increased among women served by practices that co-located EPC resources, relative to the comparator group. First trimester EPC improved in the county (17.9; 95% CI: 15.7—20.0); ED decreased in the practices (−11.1; 95% CI: -12.3— -9.9) and postpartum care improved (7.1; 95% CI: 6— 8.2) in the county. EPC participation for Black women served by the practices improved (4.4; 95% CI: 2.2—6.6), as well as early EPC (12.3; 95% CI: 9.0—15.6) and postpartum visits (10.4; 95% CI: 8.3—12.4).ConclusionsA population systems approach improved EPC participation and service utilization for Medicaid-insured women in a county population, for those in practices that co-located EPC resources, and for Black women.