The period before pregnancy is critically important for the health of a woman and her infant, yet not all women have access to health insurance during this time. We evaluated whether increased access to health insurance under the Affordable Care Act Medicaid expansions affected ten preconception health indicators, including the prevalence of chronic conditions and health behaviors, birth control use and pregnancy intention, and receipt of preconception health services. By comparing changes in outcomes for low-income women in expansion and nonexpansion states, we document greater preconception health counseling, prepregnancy folic acid intake, and postpartum use of effective birth control methods among low-income women associated with Medicaid expansion. We do not find evidence of changes on the other preconception health indicators examined. Our findings indicate that expanding Medicaid led to detectable improvements on a subset of preconception health measures.