Abstract: To investigate the safety, effectiveness and the influence factors of selective reduction during the second trimester in patients with twin pregnancy. We retrospectively analyzed the data of 12 patients with twin pregnancy who conducted the selective reduction during their second trimester. Each case was due to the structure or chromosomal abnormalities in one of two fetuses. Conditions during the surgery, gestational complications, obstetric outcomes and neonatal conditions after the surgery were assessed. All the patients were successfully conducted the selective reduction. Among the 12 patients, 4 cases had term birth baby, 3 cases had preterm birth baby, 1 case had late abortion but fetal survival, 1 case had a miscarriage and 3 cases had unbroken gestation. The average gestational weeks in those who had delivered babies (3 cases were caesarean section and 5 cases were natural delivery) were 34+1. The mean weight and height of the neonates were (2 290.00±963.52) g and (44.88±6.01) cm. No defects were found in the newborn babies. In conclusion, the selective reduction during the second trimester is safe for those patients with coexisted abnormal and normal fetus. This operation will reduce the maternal and fetal complications, as well as prevent effectively the birth of babies with congenital defect.

Key words: Pregnancy, twin, Pregnancy reduction, multifetal, Pregnancy trimester, second, Congenital abnormalities