Pelvimetry in breech and cephalic presentation.

Pelvic measurements in a group of 115 women delivering in breech presentation were compared with those in a group of 100 delivering in cephalic presentation. The average pelvic measurements were all a few mm larger in the breech cases and the average sum of the outlet diameters was significantly larger. Pelvic disproportion was not more common in breech presentation and no support was found for the theory that large pelvic measurements predispose to breech presentation. The small differences found are attributed to the moulding of the pelvis occurring during parturition.