Changes in the pelvic region of the ewe during pregnancy and parturition

Abstract

Extract

The pelvic adaptions associated with parturition have been studied for primates and some laboratory animals. No systematic work has been done on this aspect of reproductive physiology of farm animals. Hisaw and Zarrow (1950) have, recently reviewed the relevant literature. It is clear that there is considerable variation between species as to which of the pelvic joints relax during pregnancy. In the mouse, for instance, separation of the pubic symphysis occurs; in the rabbit, the sacroiliac junctions relax; while in the guinea pig both types of adaption occur. Guinea pigs and mice have been used to show that these changes in the pelvic joints are controlled by the hormone relaxin in association with the steroid sex hormones.