Although the link between the fetal environment and later life health and achievement is wellestablished, few studies have evaluated the extent to which public policies aimed at improving fetal health can generate benefits that persist into adulthood. In this study, we evaluate how a rapid expansion of public health insurance for pregnant women and infants under the Medicaid program affected the adult outcomes of individuals born between 1979 and 1993 who gained access to coverage in utero and during the first year of life. We conduct this analysis by exploiting stateand cohort-level variation in the timing and generosity of Medicaid expansions using a simulated eligibility instrumental variables model. We find that cohorts whose mothers gained eligibility for prenatal coverage under Medicaid have lower rates of chronic conditions as adults and experience fewer hospitalizations related to diabetes and obesity. We also find that the prenatal expansions increased high school graduation rates among affected cohorts. Our results indicate that expanding Medicaid prenatal coverage had sizeable long-term benefits for the next generation. * This work was supported by the Robert Wood Johnson Foundation’s Health Policy Scholars and Health & Society Scholars Programs at the University of Michigan, Ann Arbor. In addition, Laura Wherry benefited from facilities and resources provided by the California Center for Population Research at UCLA (CCPR), which receives core support (R24-HD041022) from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). We would like to thank Gabriella Conti, Andrew Goodman-Bacon, Jim House, Genevieve Kenney, Bhashkar Mazumder, Lindsay Sabik, Brendan Saloner, Daniel Schmierer, and Ben Sommers for helpful conversations and participants at presentations at AcademyHealth, American Society of Health Economics, NBER Cohort Studies, Population Association of America, Robert Wood Johnson Foundation Health and Society Scholars meeting, UCLA, University of Michigan, and the University of Illinois at Chicago, as well as Pat Barnes, Clint Carter, Frank Limehouse, and John Sullivan for their assistance in accessing the restricted data used in this project at the California, Chicago and Michigan Census Research Data Centers. Any opinions and conclusions expressed herein are those of the author(s) and do not necessarily represent the views of the U.S. Census Bureau. All results have been reviewed to ensure that no confidential information is disclosed.