The shapes of the female pelvis. Contributing factors.

OBJECTIVE To determine the etiologic factors that play a role in shaping the female pelvis. STUDY DESIGN The backgrounds of 611 pregnant women at term who underwent x-ray pelvimetry between 1962 and 1980 at term were extensively investigated. RESULTS Several facts were statistically significant. First, 24.1% of the patients had an android pelvis, although only 5.7% presented any sign of hyperandrogenism. Signs of hyperandrogenism were similarly encountered in patients with a gynecoid and any other type of pelvis. Second, the android pelvis was encountered mostly in patients exposed to strenuous physical activity during adolescence. Third, the anthropoid pelvis was encountered more often when the acquisition of erect posture was delayed beyond the usual age of 14 months, while a platypelloid pelvis was more frequent when erect posture was acquired before 14 months. CONCLUSION The final shape of the female pelvis seems to be determined by culture and environment as well as by genetics.