Effect on Making Moulding of Bony Birth Canal by Woman's Postural Change

Abstract

The object of this quosi-experimental study was to clarify the effect on making structural and functional alterations of the bony birth canal by postural change of a woman.
The subjects examined consisted of 131 pregnant women. The data used were collected by external pelvic measurement taken in various postures regarded as important in delivery, and analyzed anatomico-functionally to know a pliability of the bony birth canal. The morphological alterations of the pelvis were brought about by change of her posture.
(1) In a squatting posture, the upper part of the pelvis major was decreased in breadth due to the hinge movement of each hip bone which took place about on the ilio-pectineal lines, so that the distance between the right and left ischial tuberosities could be increased.(2) In asitting posture with the knees apart on a chair, the right and left ischial spines went away from each other, because the weight transmitted to the sacrum by the superimposed part of the vertebral colums tended to cause the sacral apex to rotate backwards.(3) In a four-foot kneelig posture, all diameters of the pelvis minor were increased, because the downward movement of the sacrum occurred in the sacro-iliac joints which were sightly loosened.
When a woman in labor changes her posture in each period of the delivery, some diameters of her bony birth canal are increased by the moulding. If she does so, it can guess that her fetal head go through the bony birth canal more easily.