Background: Teenage pregnancies have been associated with fetal growth restriction, low birth weight, preterm birth and neonatal mortality. These could be due to biological immaturity, lifestyle factors or inadequate attendance to maternity care. The objective of this study was to assess the relationship between young age of the mother and pregnancy risk factors and adverse pregnancy outcome in conditions of high-quality maternity care used by almost the entire pregnant population.

Methods: We analysed a population-based database of 26,967 singleton pregnancies during 1989-2001. Only 185 of these mothers were under 18 years old. Data were collected using a self-administered questionnaire at 20 weeks of pregnancy and clinical records of pregnancy, delivery and newborn child. The information covered maternal risk factors, pregnancy characteristics and obstetric outcomes. Odds ratios (ORs) for adverse pregnancy outcomes in teenage compared with older mothers were obtained from multiple logistic regression models.

Results: Teenage mothers smoked, were unemployed and had anaemia or chorioamnionitis more often than older mothers. On the other hand, they were overweight and had maternal diabetes less often than adults. Teenage mothers had as many instrumented deliveries (OR 0.70; 95% confidence interval 0.39-1.27) but fewer Caesarean sections (0.62; 0.39-0.97) than adults. We found no evidence for increased risk of preterm delivery, fetal growth restriction, low birth weight, or fetal or perinatal death in teenage mothers.

Conclusions: These results suggest that increased risks for adverse pregnancy outcomes in teenage pregnancies can most probably be overcome by means of high-quality maternity care with complete coverage.