The aim of the present study was to evaluate the obstetric risk in pregnant adolescents under 16 years of age. From July 1, 1970 to June 30, 1993, 188 girls aged 11-15 years were delivered at the 2nd Department of Obstetrics and Gynaecology, Vienna; 4569 primiparous women between 20 and 24 years with singleton pregnancies served as a control group. No significant differences between the two groups were found for the frequency of pregnancy-induced hypertension (2.1% vs. 3.5%), premature delivery rates (24.4% vs. 29.8%), percentage of babies weighing less than 2500 g (10.1% vs. 9.1%), mean birthweight (3082 g vs. 3117 g), frequency of intrauterine growth retardation (2.1% vs. 2.4%) and malformations (1.6% vs. 3.1%) and perinatal mortality to the end of the first week (1.1% vs. 0.5%). Adolescent mothers were found to have more spontaneous deliveries (85.1% vs. 74.9% in the control group, p < 0.005), lower Caesarean section rates (6.4% vs. 11.3%, p < 0.05) and fewer babies with a birthweight exceeding 4000 g (1.1% vs. 4.3%, p < 0.05). For the first time, the pregnancy outcome of European adolescents was studied over a period of 23 years. We conclude on the basis of our results that maternal and neonatal risk in mothers under 16 years of age does not exceed the obstetric risk in adult mothers.