[A different interpretation of the functional role of uterine fixation during natural delivery]

The Author suggests that physiologic delivery is triggered by the synergism of muscular and hydraulic forces. The first to be put into motion are the muscular contractions of the uterus, diaphragm and abdominal wall muscles; the second follow the first and cause a type of hydraulic press phenomenon that, by means of amniotic fluid, is spread to the pelvic basin during the phase in which the fetus is propelled and are only subjected to the muscular forces from myometrium contractions. Therefore, it is inaccurate to believe that these maintain all the forces of delivery. In fact, the hydraulic component of the forces of delivery, which is accepted as being the most important in terms of efficacy, doesn't rely on fixation by the uterus but rather relies on the bony surface of the pelvic basin. The Author believes that it is necessary to re-examine some of the traditional aspects of interpreting delivery because in spite of the rapid progress towards a complete understanding, the study of obstetrics has accepted without criticism and inadvertently assimilated concepts that originate and can be credited to the time of Hippocrates.