The prenatal development of the normal human skeleton: a combined ultrasonographic and post-mortem radiographic study.

Post-mortem radiography of fetuses with skeletal dysplasia is essential for diagnostic classification. Interpretation of the radiographs should be based on the knowledge of morphology and dimensions of the normal skeleton in all stages of development. A retrospective post-mortem radiographic study is presented with measurements of the lengths of the long bones and thoracic and lumbar spine. The study included 69 fetuses and neonates with a normal skeleton, whose gestational age ranged from 13-42 weeks and who died perinatally or lived for less than one week. The measurements of the long bones were plotted on growth curves obtained from a prospective longitudinal ultrasonographic investigation of another group of 63 normal fetuses from 12-40 weeks of gestation. Thoracic and lumbar spine measurements by ultrasonography were not available. The radiographic data of thoracic and lumbar spine were, therefore, compared to radiographic studies from the literature. No disagreement with these studies was found. It can be concluded that measurements of bones from standardized post-mortem radiographs in cases of questionable gestational age or defects of bone development can be compared with ultrasonographic measurements. To illustrate the usefulness of the graphs, 13 fetuses with various types of skeletal dysplasia were evaluated retrospectively.