Fetal growth in twin pregnancies

In 65 consecutive twin pregnancies, 722 measurement of fetal abdominal circumference have been obtained with ultrasound. Zygosity was established after delivery in 85% of the pregnancies. There was no difference in mean abdominal circumference measurements between monozygotic and dizygotic pregnancies. In both groups, the pattern of growth was linear throughout pregnancy in contrast to that predicted by birthweight for gestational age charts. It is suggested that increasing trunk flexion, in later twin pregnancy, may distort accurate abdominal circumference measurement.