Perinatal outcome of twin pregnancies according to maternal age

Objective To investigate the perinatal outcomes of twin pregnancies according to maternal age. Methods This is a retrospective cohort study of twin pregnancies delivered ≥24 weeks' gestation at a tertiary academic hospital from 1995 to 2016. Subjects were categorized into 5 groups according to maternal age: < 25, 25-29, 30-34, 35-39, and ≥40 years. Maternal and neonatal outcomes of each maternal age group were analyzed using the Jonckheere-Terpstra test and the linear-by-linear association test. Results A total of 1,936 twin pregnant women were included, of which 47 (2.4%), 470 (24.3%), 948 (49.0%), 417 (21.5%), and 54 (2.7%) women were aged < 25, 25-29, 30-34, 35-39, and ≥40 years, respectively. Higher maternal age was significantly associated with a higher rate of dichorionic twins and a higher risk of gestational diabetes and placenta previa. However, rates of preterm labor, preterm premature rupture of membranes, cervical incompetence, preterm delivery, preeclampsia, placenta abruption, and cesarean section were not associated with maternal age. Birth weight increased and the rate of admission to the neonatal intensive care unit (NICU) decreased with older maternal age, but other neonatal outcomes did not change with age. Maternal age was significantly associated with a lower rate of NICU admission after controlling for potential confounding factors in multivariable analysis. Conclusion Advanced maternal age in twin pregnancies was associated with increased risk of gestational diabetes, placenta previa, and higher birth weight but a lower rate of NICU admission. However, other outcomes were not significantly associated with maternal age.