Analysis of shrinkage in human fetal diaphyseal lengths from fresh to dry bone using Petersohn and Köhler's data.

Calculation of gestational age from forensic fetal remains may be problematic. If soft-tissue indicators are not available, then diaphyseal lengths obtained through sonograms on living fetuses in utero or radiographs of long bones can be compared to known European standards, such as Fazekas and Kósa (1978) and Olivier and Pineau (1958, 1960). Radiographic comparison to these European standards, however, requires a correction factor for diaphyseal shrinkage from fresh to dry states. Percent shrinkage is calculated for six diaphyses (humerus, ulna, radius, femur, tibia and fibula) from Petersohn and Köhler's data published in Fazekas and Kósa (1978:362-369). Average shrinkage, standard deviation, minimum and maximum values are calculated for each diaphysis and for all diaphyses during 4-10 lunar months (LM) and newborns. Corresponding average and standard deviation values are as follows: 4 LM-10.09% +/- 2.67%; 5 LM-5.74% +/- 0.84%; 6 LM-3.48% +/- 0.49%; 7 LM-2.32% +/- 0.16%; 8 LM-2.18% +/- 0.51%; 9 LM-1.76% +/- 0.14%; 10 LM-1.90% +/- 0.59%; and newborns-1.28% +/- 0.55%. Analysis of these values suggests that percent shrinkage steadily declines as the fetus ages. This pattern presumably reflects calcification of bone during growth and development in utero. These findings demonstrate a significant shrinkage in the diaphysis early in development, which may alter accurate age estimation in the earliest fetal age groups.