OBJECTIVE Analysis of obstetrical risk factors in teenage primiparous pregnancies in Reunion Island (4% of total births). METHODS Retrospective study, between 2001 and 2002, comparing primiparous adolescents (13-17 years, n = 365), with primiparous controls (18-29 years, n = 2050). The analysis included demographical factors, maternal medical histories, prenatal follow-up, obstetrical risk factors, delivery modes and neonatal characteristics. RESULTS Adolescents attended on average 8 prenatal consultations, however 4% had poor prenatal care (less than 3 visits, OR 4.2, P < 0.001 vs controls). They presented less gestational diabetes, but there were no differences concerning pre-existing hypertension, hypertensive disorders of pregnancy, medical reasons of hospitalisation between the two groups. Mode of delivery was more favorable in adolescents (half rate of caesarean sections, shorter duration of membrane ruptures). Nevertheless, adolescents presented a higher risk of severe prematurity (<32 Weeks gestation, incidence 3.6% vs 1.6%, OR 2.3, p = 0.008). CONCLUSIONS With optimal prenatal care (more than 90% of our cohort), primiparous adolescents present globally a favorable course of their pregnancies and have better deliveries than their young (18-29 years) counterparts. However, there is a significant risk of severe prematurity requiring special care for these pregnancies.