Maternal age and adverse pregnancy outcome: a cohort study.

OBJECTIVE To examine the association between maternal age and a wide range of adverse pregnancy outcomes after adjustment for confounding factors in obstetric history and maternal characteristics. METHODS This was a retrospective study in women with singleton pregnancies attending the first routine hospital visit at 11 + 0 to 13 + 6 weeks' gestation. Data on maternal characteristics, and medical and obstetric history were collected and pregnancy outcomes ascertained. Maternal age was studied, both as a continuous and as a categorical variable. Regression analysis was performed to examine the association between maternal age and adverse pregnancy outcome including pre-eclampsia, gestational hypertension, gestational diabetes mellitus (GDM), preterm delivery, small-for-gestational age (SGA) neonate, large-for-gestational age (LGA) neonate, miscarriage, stillbirth and elective and emergency Cesarean section. RESULTS The study population included 76 158 singleton pregnancies with a live fetus at 11 + 0 to 13 + 6 weeks. After adjusting for potential maternal and pregnancy confounding variables, advanced maternal age (defined as ≥ 40 years) was associated with increased risk of miscarriage (odds ratio (OR), 2.32 (95% CI, 1.83-2.93); P < 0.001), pre-eclampsia (OR, 1.49 (95% CI, 1.22-1.82); P < 0.001), GDM (OR, 1.88 (95% CI, 1.55-2.29); P < 0.001), SGA (OR, 1.46 (95% CI, 1.27-1.69); P < 0.001) and Cesarean section (OR, 1.95 (95% CI, 1.77-2.14); P < 0.001), but not with stillbirth, gestational hypertension, spontaneous preterm delivery or LGA. CONCLUSIONS Maternal age should be combined with other maternal characteristics and obstetric history when calculating an individualized adjusted risk for adverse pregnancy complications. Advanced maternal age is a risk factor for miscarriage, pre-eclampsia, SGA, GDM and Cesarean section, but not for stillbirth, gestational hypertension, spontaneous preterm delivery or LGA.