Measurement of foetal femoral and tibial lengths as a means of radiologic estimation of gestational age at birth.

The lengths of the femur and tibia were measured in lower limb radiographs of 159 newborn infants whose gestational age were determined by both maternal history and a Dubowitz examination. There are strong linear relationships between lengths of tibia and femur with gestational age and birth weight. The correlation coefficients between femoral and tibial lengths and gestational age were respectively 0.97 and 0.94. There is no significant difference in length of the lower limb bones between the sexes.