Maternal age and adverse pregnancy outcomes: a population-based register study in Wuhan, China, 2011-2016

Abstract Background A trend towards increasing maternal age has been witnessed in China. Evidence from high-income countries has shown that older women have higher risks of various adverse pregnancy outcomes. However, few large, contemporary, population-based studies have adjusted for potential confounders in examining the association between maternal age and adverse pregnancy outcomes in China. Methods Data from the Wuhan Maternal and Child Health Management Information System including all women aged ≥20 years with live singleton pregnancies in 2011-2016 were analyzed. A range of adverse pregnancy outcomes including pregnancy induced hypertension disorder(PIH), gestational diabetes mellitus(GDM), cesarean delivery, postpartum hemorrhage, preterm birth, small-for-gestational age (SGA), large-for-gestational age (LGA), and 5-min Apgar score<7 among women aged 20-24, 30-35 and ≥40 years were compared with women aged 25-29 years using binary logistic regression models, with social-demographic characteristics, pre-pregnancy BMI, parity, and fetal gender adjusted. Subgroup analyses by stratifying on parity were also performed. Results 415,632 women were included during the study period. Among them, 91536(22.0%) were aged 20-24 years, 203687(49.0%) were aged 25-29 years, 89883(21.6%) were aged 30-34 years, 26271(6.3%) were aged 35-39 years, and 4255 (1.0%) were aged ≥40 years. After adjusting for the potential confounders, older maternal age (≥30 years) was associated with higher risks of PIH, GDM, cesarean delivery, preterm birth, LGA, and 5-min Apgar score<7, but not with SGA. Relative to older multiparous women, older nulliparous women were more likely to experience cesarean delivery, preterm birth, and 5-min Apgar score<7. Conclusion Older maternal age is independently associated with various adverse pregnancy outcomes. The risks may occur earlier than the commonly used definition of advanced maternal age, and may also differ by parity. Ensuring age and parity specific clinical counseling, antenatal surveillance, and health interventions may be of great significance to improve older mother’s pregnancy outcomes.