[Association between maternal age and adverse pregnancy outcome in twin pregnancy].

Objective: To study the association between maternal age and adverse pregnancy outcome in twin pregnancy.

Methods: The clinical data of 2 363 women with twin pregnancy from January 2006 to June 2016 were retrospectively reviewed. According to the age, the women were divided into six groups: <20 years (n=15), 20-24 years (n=158), 25-29 years (n=894), 30-34 years (n=936), 35-39 years (n=320), and ≥40 years group (n=40). The above groups were compared in terms of related baseline features and incidence rates of adverse pregnancy outcomes (preterm birth, birth defect, stillbirth in late pregnancy and small-for-gestational-age birth). A generalized estimating equation was used to investigate the risk of adverse pregnancy outcomes in different age groups.

Results: After control for the factors including place of residence, primipara, pregnancy pattern, and gestational diseases, the incidence rates of very preterm birth and moderately preterm birth in the ≥40 years group were 2.60 and 1.99 times than those in the 25-29 years group respectively (P<0.05). The incidence rates of very preterm birth and late preterm birth in the 20-24 years group were 1.99 and 1.33 times than those in the 25-29 years group respectively (P<0.05). The incidence rates of stillbirth in late pregnancy in the <20 years group, the 20-24 years group, and the ≥40 years group were 9.10, 2.88 and 3.97 times than those in the 25-29 years group respectively (P<0.05). The incidence rates of small-for-gestational-age birth in the <20 years group and the 35-39 years group were 2.70 and 0.73 times than those in the 25-29 years group respectively (P<0.05).

Conclusions: In twin pregnancy, pregnant women, aged <20 years, have a higher risk of smaller-for-gestational-age birth and stillbirth in late pregnancy, those aged ≥40 years have a higher risk of very preterm birth, moderately preterm birth and stillbirth in late pregnancy, and those aged 20-24 years have a higher risk of very preterm birth, late preterm birth and stillbirth in late pregnancy.