Relationship between maternal age and the risk of adverse pregnancy outcomes: a retrospective cohort study in China

Abstract

Abstract Background: Maternal age at childbearing has been dramatically increasing worldwide. The problems of adverse obstetric outcomes caused by extremes of maternal ageare more common. This study aimed to analyze the associations between maternal age and the risk of adverse pregnancy outcomes. Methods: We performed a population-based study consisting of 108,706 singleton pregnant women whose newborns were delivered after 20 weeks' gestation between January 2012 and December 2015 in China. Participants were divided into four groups according to maternal age at delivery (19 years or younger; 20-34 years; 35-39 years; 40 years or older). Logistic regression models were used to assess the associations between maternal age and adverse pregnancy outcomes with women aged 20–34 years as the reference group. Results: Advanced maternal agewas associated with an elevated risk of almost all adverse pregnancy outcomes. Young maternal age was associated with increased risk of preterm birth (RR 1.48, 95% CI 1.31–1.67), low birth weight (RR 1.69 95% CI 1.51–1.90), small for gestational age (RR 1.44, 95% CI 1.32–1.57), an Apgar score < 7 at 5 min (RR 1.54, 95% CI 1.08–2.21), and fetal death (RR 1.82, 95% CI 1.22–2.71), as well as decreased risk of gestational diabetes mellitus (RR 0.20, 95% CI 0.13–0.29), gestational hypertension (RR 0.29, 95% CI 0.15–0.56), preeclampsia (RR 0.29, 95% CI 0.17–0.50), premature rupture of membranes (RR 0.29, 95% CI 0.22–0.39), postpartum hemorrhage (RR 0.50, 95% CI 0.33–0.76), cesarean delivery (RR 0.42, 95% CI 0.39–0.47), macrosomia (RR 0.34, 95% CI 0.23–0.49), and fetal distress (RR 0.48, 95% CI 0.38–0.61). Conclusions: Advanced maternal age predisposes women to adverseobstetric outcomes. Young maternal age manifests a bidirectional effect on adverse pregnancy outcomes. The findings can be used to improve women's antenatal care and management.