In the case of pelvic girdle instability, the ligaments that hold the pelvis together in the area of the pubic symphysis have become loose. The main causes are physical stress, hormonal changes during pregnancy, and previous pregnancies or births. Pelvic girdle instability is characterized, among other symptoms, by pelvic pain, low back pain, SI joint irritation, and restricted mobility.
Pregnant women are most affected by pelvic girdle instability combined with pelvic pain. Five to nine per cent of all pregnant women will develop pelvic girdle instability during pregnancy or the birth of their child.