We conduct a randomized controlled trial that provides pregnant and immediate postpartum women with improved access to family planning through counseling, free transportation to a clinic, and financial reimbursement for family planning services over two years. We study the effects of our intervention on child growth and development outcomes among 1,034 children born to participating women directly before the intervention rollout. We find that children born to mothers assigned to the family planning intervention arm were 0.28–0.34 standard deviations taller for their age and 10.7–12.0 percentage points less likely to be stunted within a year of exposure to the intervention. Children born to mothers assigned to the intervention arm also scored 0.17–0.20 standard deviations higher on a caregiver-reported measure of cognitive development after two years of intervention exposure. Although the nonmeasurement of children is a challenge in our study, our estimates are robust to multiple methods of correcting for potential attrition bias. Our results are consistent with models of fertility that link couples’ fertility decisions to child health and human capital. Our results also suggest that improved access to family planning might have positive downstream effects on child health beyond contraceptive use and fertility outcomes.