Birth Weight Discordance and Neonatal Outcomes in Uncomplicated Twin Pregnancies

OBJECTIVE: To evaluate the association between birth weight discordance (BWD) and neonatal outcomes in uncomplicated twin pregnancies. STUDY DESIGN: Uncomplicated twin pregnancy was defined as without major anomaly, intrauterine fetal demise, delivery before 24 weeks of gestation, and unique complications of monochorionic twins. Abnormal umbilical artery Doppler was defined as persistent absence or reverse of end-diastolic flow. Neonatal death was death within 28 days after delivery. A poor neonatal outcome was defined as a fetus with neonatal death, severe respiratory distress, hemodynamically significant patent ductal arteriosus, or intraventricular hemorrhage more than grade II. RESULTS: A total of 864 uncomplicated twins who were delivered at Linkou Chang Gung Memorial Hospital from 2012 to 2018 were included in this study. Gestational age of delivery and abnormal umbilical artery Doppler of the smaller twin are the 2 variables in predicting neonatal death. BWD was found as an independent factor to foretell poor neonatal outcomes of the smaller fetus but not the larger twin in a twin pair. With BWD > 25%, the smaller fetus has a higher incidence of having poor neonatal outcomes than does the larger fetus. CONCLUSION: Increasing BWD is associated with the poor neonatal outcome of the smaller twin, and BWD > 25% could be considered as severe discordance in uncomplicated twin pregnancies.