BACKGROUND Adverse birth outcomes are more common among adolescent versus adult mothers, but little is known about school‐based services that may improve birth outcomes in this group. METHODS Data from Waves I and IV of the National Longitudinal Study of Adolescent Health were analyzed. Girls and women who gave birth to singleton live infants after Wave I and before age 20, were still in secondary school while pregnant, and had complete data (N = 402) were included. Mothers reported infants' birthweight and gestational age. School administrators reported whether family planning counseling, diagnostic screening (including sexually transmitted diseases [STDs]), STD treatment, and prenatal/postpartum health care were provided on‐site at school at Wave I. Multilevel models adjusted for individual and school characteristics were conducted. RESULTS Few schools offered reproductive health care services on‐site. In multilevel analyses, availability of family planning counseling (Est. β = 0.21, 95% confidence interval [CI] 0.04‐0.38 p < 0.05) and prenatal/postpartum health care (Est. β = 0.21, 95% CI 0.02‐0.40 p < 0.05) were significantly associated with increased infant birthweight. No services examined were significantly associated with increased gestational age. CONCLUSIONS Some school‐based reproductive health services may improve subsequent birth outcomes among adolescent mothers. Future analyses should examine the mechanisms by which services impact birth outcomes.