To increase access to highly effective contraception and improve reproductive autonomy, a growing number of state Medicaid programs pay for the provision of immediate postpartum long-acting reversible contraception (LARC) in addition to providing a global payment for maternity care. Using Pregnancy Risk Assessment Monitoring System data, we examined postpartum LARC use both overall and by race and ethnicity among respondents with Medicaid-paid births during the period 2012-18 in eight states that implemented immediate postpartum LARC payment and eight states without it. Using a quasi-experimental difference-in-differences design, we found that the policy resulted in an overall 2.1-percentage-point increase in postpartum LARC use. Our triple-differences analysis found no significant change among White mothers and a 3.7-percentage-point increase in use among Black mothers compared with White mothers. Additional research is needed to determine whether this increase was aligned with patients' preferences and whether hospitals' immediate postpartum LARC policies and practices take a patient-centered approach that supports reproductive autonomy and equity.