A radiographic study of the human fetal spine. 3. Longitudinal growth.

Regression equations are presented which describe the growth in length of the various regions of the vertebral column in the human fetus. From 8 weeks on the thoracic is always the longest region and the sacral the shortest, while the lumbar region is longer than the cervical. From the regression equations predictions of fetal vertebral length can be made from fetal age: this should be useful in obstetric practice when diagnostic ultrasound techniques are being employed for the diagnosis of growth disorders and skeletal abnormalities. A different developmental pattern emerges when average 'vertebral units' for each region are compared. The lumbar vertebrae are always the largest with the thoracic, cervical and sacral vertebrae being progressively smaller.