A prospective longitudinal study of growth in twin gestations compared with growth in singleton pregnancies. II. The fetal limbs.

The assessment of fetal growth is crucial in twin gestations, since the information gained often has an impact on pregnancy management. The measurement of the fetal anatomy by ultrasound enables us to follow the growth and development of the fetus. However, the pattern of fetal growth in twin gestations has not yet been precisely characterized in prospective studies. In this light, we initiated a prospective longitudinal study and sonographically examined 35 patients with twin gestations every 3 weeks from the 15th week until delivery. Multiple biometric parameters were measured, including the femur length, humerus length, ulna length, and tibia length. The results of our study showed that growth of these long bones was not significantly different between twins A and B throughout gestation and that the growth velocity between twins and singletons was not significantly different. The incremental growth, although significantly less in twins than in singletons, was so small that it was judged not to be of clinical importance to warrant the generation of separate nomograms for the evaluation of growth in twin gestations.