Background: Since the 1970-ies Sweden has actively developed strategies in social care, education and health care in order to counteract the negative consequences of adolescent parenthood. The aims of this study are to determine the annual incidence of singleton delivery among adolescents 1973-2010 and analyse obstetric and neonatal outcomes. Methods: A retrospective cohort study, using data from the Swedish Medical Birth Register was conducted. All singleton deliveries in Sweden between 1973 and 2010 were included. Totally 1,941,940 women had 3,761,576 deliveries during the period. Analyses of obstetric and neonatal outcome were restricted to 1992-2010. Adolescents were subdivided into three groups: less than16 years (n = 472), 16-17 years (n = 5376), 18-19 years (n = 23560). The reference group consisted of women age 20-30 years (n = 893505). Data were analysed using multivariate logistic regression models adjusted for confounding factors and presented as crude and adjusted odds ratios with 95% confidence interval. Results: The annual incidence of teenage births decreased significantly from 7.7 to 1.6%. Teenagers were more likely to deliver normally vaginally (aOR 1.70 (95% CI 1.64-1.75), less likely to have Caesarean section (aOR 0.61 (95% CI 0.58-0.64), and had a greater risk of delivering prematurely (less than 28 weeks)(aOR 1.61 (95% CI 1.31-2.00), but did not have more small-for-gestational-age babies (aOR 1.07 (95% CI 0.99-1.14). Risks of placenta previa, postpartum haemorrhage greater than 1000 ml and perineal rupture were significantly lower among teenagers. Although the rate with Apgar score less than 7 at 5 minutes was similar the teenagers neonates showed less fetal distress and meconium aspiration. Conclusion: Adolescent births have steadily decreased in Sweden. Adolescents were more likely to be delivered vaginally than the adult women. The risks for obstetric maternal complications for adolescents were lower than for adult women except for the risk of prematurity.