Sexual Dimorphism of the Bony Pelvis: Morphometric Differences and Their Obstetric Significance

The article is a literature review of sexual dimorphism of the human bony pelvis. Qualitative and metric sex differences of the hip bone, sacrum, pelvic inlet, cavity and outlet are summarized, together with the Caldwell–Moloy classification of pelvic types, the age at which dimorphism develops, the role of sex hormones, and the evolutionary concept of the "obstetric dilemma". The obstetric significance of pelvic dimensions (true, diagonal and obstetric conjugates, interspinous and intertuberous diameters) and the contribution of external pelvimetry, ultrasound, CT and MRI to the assessment of the birth canal are discussed. The limitations of pelvimetry for prediction of the course of labour and the population variability of pelvic morphology are emphasized. The review is based on published sources; no original patient data or statistics are presented.