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

Since the available data on growth in twin gestations have been derived from retrospective cross-sectional studies with varying results, a prospective longitudinal study was initiated to assess fetal head growth in twin gestations as compared to singleton pregnancies. In uncomplicated twin gestations, growth of the fetal head, based on the increment in growth over time and the rate of growth throughout pregnancy, was found not to be significantly different than in singleton pregnancies. In light of these findings, current nomograms derived from measurements obtained in singleton pregnancies remain useful for evaluating fetal head growth in twin gestations.