OBJECTIVE: Premature infants have increased health care utilization after initial discharge compared with term infants. Young maternal age has been shown to impact health care utilization among term infants, but little is known about the impact of maternal age on health care utilization among premature infants. We compared health care utilization among premature infants of adolescent (aged < or = 19 years) and young adult (aged 20-29 years) mothers, hypothesizing that premature infants of adolescent mothers would have increased acute care utilization, while having decreased preventive care utilization. METHODS: In this retrospective cohort study, we analyzed health care utilization of premature infants born to adolescent mothers (n = 76) compared with premature infants born to young adult mothers (n = 587) within a cohort of premature infants born between 1998 and 2001 in an integrated health care delivery system. RESULTS: After controlling for illness severity, premature infants born to adolescent mothers had significantly increased odds of medical rehospitalizations (odds ratio 3.57, 95% confidence interval, 1.81-7.05) and emergency department visits (odds ratio 3.67, 95% confidence interval, 2.11-6.39) during the first year after initial discharge compared with premature infants born to young adult mothers. Differences in rehospitalization rates were significant within the first 3 months after discharge (P < .001). Frequency of preventive care visits was not significantly different between the two groups. CONCLUSIONS: Despite similar severity of chronic illness and similar preventive care utilization, premature infants born to adolescent mothers had significantly increased rates of rehospitalizations and emergency department visits compared with premature infants born to young adult mothers.