A Morphometric Study of Sex Differences in Fetal Ilia

Considerable debate has concentrated on whether human fetal skeletal remains exhibit sexual dimorphism. Most attention has focused on the greater sciatic notch of the ilium, since it is a gross morphological characteristic with known sex differences in the adult and is easily seen in fetal skeletal remains. Previous traditional morphometric analyses of the fetal sciatic notch have, however, led to ambiguous results. The purpose of this study is to determine whether differences between the sexes can be discerned when modern morphometric techniques are applied.

Photographs of the ventral side of 133 fetal ilia of known age and sex from the Trotter Collection of Washington University are digitized, and the trace coordinates used for all subsequent analyses. Elliptic Fourier analysis followed by calculation of a discriminant function indicates that there are significant shape differences between male and female fetal ilia (81.8% of females correctly classified, 74.0% of males correctly classified). In order to identify these shape differences, a finite line skeleton is fit to each tracing and used to locate homologous landmarks that encompass the sciatic notch. These landmarks are then used in a Euclidean distance matrix analysis to localize the form differences between the sexes. The comparison of distances shows there are no statistically significant differences between the sexes localized around the greater sciatic notch.