Significance Improving access to family planning may promote contraceptive use after childbirth and reduce the likelihood of closely spaced high-risk births; however, empirical evidence for these claims is limited. We present findings from a field experiment that examines the causal impact of a broad-based family-planning intervention on postpartum contraceptive use and fertility over a 2-y period, which allows us to assess impact on high-risk short pregnancy intervals. Our findings demonstrate that the benefits of family planning extend beyond contraceptive use to improve fertility and healthy birth spacing. Evidence from this study will contribute to the design of effective family-planning programs and to informing the ongoing policy debate about how such programs impact longer-term health and development more broadly.