Prediction of growth discordance in twins with the use of abdominal circumference ratios

Abstract

Objective: The purpose of this study was to assess the accuracy of sonographic prediction of twin birth weight discordance using the abdominal circumference ratio.

Study design: This was a prospective cohort of diamniotic twin gestations that underwent serial ultrasound examinations every 2 to 4 weeks from 11 to 38 weeks of gestation. Birth weight discordance was defined as > or =25% difference in birth weight, relative to the larger twin. The sensitivity, specificity, and predictive values for the abdominal circumference ratio were assessed for the prediction of growth discordance.

Results: Of 503 diamniotic twin pregnancies, 64 pregnancies (12.7%) had discordant fetal growth. The abdominal circumference ratio could be measured consistently throughout gestation in 100% of twin pairs. Receiver operating curve analysis showed that the abdominal circumference ratio was a good predictor of birth weight discordance (area under the curve = 0.80). An abdominal circumference ratio cutoff of 0.93 yielded a sensitivity and specificity of 61% and 84%, respectively.

Conclusion: Twin birth weight discordance may be predicted at any gestational age with an abdominal circumference ratio <0.93.