Accuracy of sonographic fetal biometry in estimating intertwin size discordance at birth.

Objective: To determine the accuracy of estimated fetal weight (EFW) and abdominal circumference (AC) discordance in diagnosing large birthweight (BW) discordance and selective fetal growth restriction (sFGR).

Methods: Retrospective cohort study of patients with twin pregnancies followed at a tertiary center (N = 1065). We determined the accuracy of intertwin fetal size discordance (based on either EFW or fetal AC) at the last ultrasound exam before birth in estimating birthweight discordance and in diagnosing sFGR at birth.