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.