Anatomy in Brief

The pelvic girdle is made up of 3 bones, the sacrum flanked by 2 innominate bones. The symphysis pubis is a fibrocartilaginous structure that sits
at the front of the pelvis, connecting and holding the 2 innominate bones of the pelvis together.

The joints at the back of the pelvis are called the sacroiliac joints. During pregnancy, hormones soften supporting ligaments in these joints to prepare for labour, hence decreasing stability in the pelvis.
This instability may cause peripartum pelvic pains.