Does Young Maternal Age Increase the Risk of Adverse Obstetric, Fetal and Neonatal Outcomes?

Abstract

Previous studies have reported that infants born to adolescent mothers in both developed and developing countries have higher risks of inadequate prenatal care, low birth weight (LBW), and premature birth. The effect of maternal youth on adverse maternal and neonatal outcomes is unclear. There are conflicting data on the possible association between teenage pregnancy and maternal anemia, fetal death, or other adverse outcomes. This population-based retrospective cohort study investigated the role of young maternal age on increasing risks of adverse obstetric, fetal, and perinatal outcomes. During the study period (1994–2001), medical records were obtained from the database of a university hospital for 8514 first-born singleton infants born to primiparous women aged between 14 and 30 years. Regression models using age as a continuous variable assessed the associations between maternal age and each maternal and perinatal outcome to obtain an estimate of the crude and adjusted relative risks (RRs) of young maternal age. RRs at age 16 were compared with those at age 20 and 25 years. Maternal outcomes assessed were anemia during pregnancy, pre-eclampsia, and proteinuria in women who were normotensive when admitted, cesarean section, operative vaginal delivery, and postpartum hemorrhage. Perinatal outcomes investigated included premature birth (before 37 weeks’ gestation), LBW (<2500 g), birth weight ≥4000 g, admission to the neonatal intensive care unit, and fetal death (delivery of a dead infant after 22 weeks’ gestation). Both crude and adjusted RRs of anemia and fetal death consistently increased with younger maternal age in comparison to mothers aged 20 and 25 years. The adjusted RR of fetal death and anemia for a 16-year-old mother compared to a 20-year-old mother were 1.37 (95% confidence interval, 1.09–1.70; P < 0.038) and 1.27 (95% confidence interval, 1.15–1.40; P < 0.001), respectively. However, mothers aged 16 years had significantly decreased risks of pre-eclampsia, cesarean section, operative vaginal delivery, and postpartum hemorrhage in comparison to mothers aged 20 years. After controlling for confounding factors, the prevalence of prematurity and LBW in the offspring of 16-year-old mothers was not related to young maternal age. These findings indicate that younger maternal age has a consistent association with higher risks of fetal death and maternal anemia compared to older maternal age, and with lower risks of pre-eclampsia, cesarean section, operative vaginal delivery, and postpartum hemorrhage.