Developmental age estimated by bone-length measurement in human fetuses.

The lengths of 491 long bones of the extremities derived from 193 freshly delivered human fetuses of 7 to 22 weeks fertilization age were measured. Fetuses delivered after spontaneous abortion, twin pregnancy, or known maternal disease were excluded. The correlation between fetal age (measured by crown-rump length) and bone length was linear. The term "developmental age" was used for bone length-derived age values. Developmental age can be determined from the length of even a single bone, i.e., when mechanical injury of the delivered fetus inhibits crown-rump length measurement. The results could aid researchers dealing with human embryology, clinicians performing fetal tissue transplantation, and could be applied in forensic medicine as well.