[Obstetrical study of the pelvis: a historical overview]

The female pelvis is fundamental to life itself, but it took ages to grasp this truism. During Antiquity, physicians had no need for the concepts of pelvic dystocia and cephalopelvic disproportion. When Aranzo (16th century), a practising physician, stated that a disproportion between the size of the fetus and that of the bony pelvis was the main culprit of difficult labor, his suggestion was overlooked, so much so that it was Hendrik van Deventer (1701) who came to be coined "father of the pelvic theory". The need for an accurate knowledge of the dimensions of the maternal pelvis and of the fetal skull became imperative in the middle of the 18th century, when forceps extraction had become popular. Levret, but above all William Smellie, made valuable contributions to the pelvic theory, which, however, were weakened by Baudelocque's fallacies concerning the intrinsic value of external pelvimetry. After the first quarter of the 19th century, the epicenter of scientific obstetrics moved to Germany and Austria, and German-speaking practitioners, e.g. Michaelis, Litzmann, and the Naegele, deepened our insight in the mechanism of labor. After the discovery of the X-rays (1895), the use of instrumental pelvimetry declined, but the clinical breakthrough of radiopelvimetry was delayed until the twenties of this century. Radiopelvimetry, a very valuable technique indeed, dispensed a large number of mothers from undergoing abdominal delivery. However, awareness of the hazards of fetal-maternal exposure to ionizing radiation pushed ante- and intrapartum radiopelvimetry from the scene. Thanks to the progress of chemistry, pharmacology and electronics, "dynamic pelvimetry" became the fad, heralded by what is called "active management of labour". The fetus now assumed the role of "dynamic pelvimeter". The historical circle was closed.