The ChiTwiMC Cohort focusing on the serious complications of twin pregnancy, establish a multicenter large prospective mother-child cohort of twin pregnancy covering pregnancy→neonatal period→early childhood, and a multi-variety, multi-stage biobank for the study of adverse outcomes of twin pregnancy. The ChiTwiMC Cohort is planning to recruit 2000 pregnant women aged 18-45 years from 9 large obstetrical center of major University-affiliated Hospitals across China, between December 2023 and May 2026. All women will be enrolled prior to 14 wks of gestation, pregnancy was followed up at 22-28 wks, 30-38 wks of gestation, delivery, postpartum 42 days, 6 months, 12 months. Data including demographics, medical history, reproductive history, clinical diagnosis, treatment information, and pregnancy and birth outcomes will be collected via electronic data capture system. Track the outcome of severe maternal-fetal complications and early neonatal outcomes of twins, and collect biological samples, including peripheral venous blood, hair and cervicovaginal secretions from pregnant women, placenta tissue, amniotic fluid and unbilical cord blood at delivery, meconium and hair from newborns, buccal mucosa from infants and peripheral venous blood from the husband.
