Biometric Characteristics of the Pelvis in Female-to-Male Transsexuals

The objective of the study was to evaluate the metric features of pelvises of 24 female-to-male (FtM) transsexuals as compared
to control groups of 24 healthy males and 24 healthy females. The participants had their pelvises X-rayed with the same X-ray
apparatus and in the same position. Seventeen measurements were taken on the basis of X-ray pictures of FtM transsexuals’
pelvises and both comparison groups. Additionally, their body height was compared. The results showed that FtM transsexuals
having female body height represent an intermediate size of three pelvic features and male values of five variables. In order
to develop a model based on metric variables of the pelvis that would best discriminate the FtM transsexuals, the control
females, and the control males, a discriminant analysis was applied. The model included four variables out of 17 metric features:
the height of the pubic symphysis, the greatest pelvic breadth, the interischial distance, and the acetabular diameter. The
model was found to be the best in discriminating males from females and FtM transsexuals, but considerably less effective
in discriminating transsexuals from the two control groups. The results demonstrate that a number of FtM transsexuals’ pelvic
measurements reveal “masculinization,” which confirms current results demonstrating a shift in the somatometric traits of
transsexual females towards male traits. A discriminant analysis based only on pelvic metric features shows some differences
between the size of the pelvis and chromosomal sex in FtM transsexuals, which might indicate a biological basis for gender
identity disorder.