Teenage pregnancy and adverse birth outcomes: a large population based retrospective cohort study

Background Whether the association between teenage pregnancy and adverse birth outcomes could be explained by deleterious social environment, inadequate prenatal care, or biological immaturity remains controversial. The objective of this study was to determine whether teenage pregnancy is associated with increased adverse birth outcomes independent of known confounding factors. Methods We carried out a retrospective cohort study of 3 886 364 nulliparous pregnant women <25 years of age with a live singleton birth during 1995 and 2000 in the United States. Results All teenage groups were associated with increased risks for pre-term delivery, low birth weight and neonatal mortality. Infants born to teenage mothers aged 17 or younger had a higher risk for low Apgar score at 5 min. Further adjustment for weight gain during pregnancy did not change the observed association. Restricting the analysis to white married mothers with ageappropriate education level, adequate prenatal care, without smoking and alcohol use during pregnancy yielded similar results. Conclusions Teenage pregnancy increases the risk of adverse birth outcomes that is independent of important known confounders. This finding challenges the accepted opinion that adverse birth outcome associated with teenage pregnancy is attributable to low socioeconomic status, inadequate prenatal care and inadequate weight gain during pregnancy.