Effects of maternal age on pregnancy: a retrospective cohort study

Abstract

To determine the pregnancy outcomes related with maternal age in China. A total of 110 450 cases were selected and divided into 6 age groups at intervals of 5 years. The clinical data were collected from 39 hospitals in mainland China. All deliveries were after 28 weeks of completed gestation in 2011. The unadjusted binary-logistic regression was employed for statistics. The mean age of all pregnant women was 28 ± 5 at the time of delivery. The advanced age groups (35-39 yr and ≥ 40 yr) had higher risks than the 25-29 age group for pregestational diabetes [odds ratio (OR), 2.2 and 3.8], chronic hypertension (OR, 4.6 and 6.5), leiomyoma (OR, 4.2 and 5.8), gestational diabetes (OR, 2.6 and 3.5), preeclampsia (OR, 2.5 and 3.6), postpartum hemorrhage (OR, 1.5 and 1.7), premature delivery (OR, 1.8 and 2.4), placenta previa (OR, 2.7 and 4.0), placental abruption (OR, 1.4 and 2.5), cesarean delivery (OR, 2.1 and 2.5), macrosomia (OR, 1.2 and 1.2), low birth weight neonates (OR, 1.6 and 2.3) and perinatal mortality (OR, 1.6 and 3.7). The adolescent group had higher risks than the 25-29 age group for anemia (OR, 1.4), preeclampsia (OR, 1.6), preterm birth (OR, 2.1), low birth weight neonates (OR, 2.3) and perinatal mortality (OR, 3.6). Maternal and neonatal risks are higher during both the adolescent and advanced maternal ages. And the age group of 20-30 years has the lowest risk for pregnancy and delivery.