Pregnancy complications among nulliparous and multiparous women with advanced maternal age: a community-based prospective cohort study in China

Background This study aimed to evaluate the incidence rates and risks of pregnancy complications among nulliparous and multiparous women with advanced maternal age (AMA, >= 35 years) in China. Methods We performed a community-based prospective cohort study of 10,171 pregnant women in selected two sub-districts and 11 towns of Liuyang from 2013 to 2015. All subjects were followed up from the first prenatal care (at <= 12 weeks) to delivery, and risks of pregnancy complications were compared by parity and maternal age groups. Results Among nulliparas, women with AMA showed significantly increased risks for gestational hypertension (OR 8.44, 95%CI 1.68-2.88), preeclampsia/eclampsia (OR 9.92, 95%CI 4.87-18.78), premature rupture of membrane (OR 6.84, 95%CI 2.00-17.69), as compared to women in the 20-29-year age group. Among multiparas with AMA, increased risks were found for gestational diabetes mellitus (OR 3.29, 95%CI 1.76-5.94), anemia (OR 1.85, 95%CI 1.25-2.69), polyhydramnios (OR 3.29, 95%CI 1.56-6.64), premature rupture of membrane (OR 5.14, 95%CI 2.12-12.29), and preterm labor (OR 1.89, 95CI 1.42-2.50). Conclusions Women with AMA were associated with increased risks of pregnancy complications, and complications with increased risks differed in nulliparas and multiparas. Women with AMA should be identified as a high-risk group in clinical practice.