[Biometry of the large bones of fetal extremities in the 3d trimester]

Ultrasound measurement of head, thorax and the limb bones femur, tibia, humerus and radius was made of 285 fetuses with known gestational age. In addition measurements of the fibula were obtained in 120 fetuses and of the ulna in 125 fetuses. With the use of these data a normal growth curve for each limb bone was established, which can be helpful in detecting late fetal limb malformations as heterozygous achondroplasia. All limb bones show a nearly linear growth rate so that the length of the bones can alternatively be used to determine gestational age. The linear relationship between growth of the limb bones and the fetal head can be used to diagnose fetal head malformations as microcephaly.