Backache during pregnancy occurs as a result of ligaments stretching under the influence of progesterone, and the mechanical problems caused by the weight of the uterus. One of the functions of progesterone is to loosen ligaments, primarily to allow the pelvis to enlarge a little to accommodate the growing uterus. The effect on the ligaments of the spine, however, is to increase the likelihood of the development of mechanical back pain, particularly in the lower back. Correct posture, exercise and effective support may minimise the symptoms and reduce the likelihood of the condition becoming chronic (i.e. persisting after delivery). Very rarely this may predispose to the development of a prolapsed intra-vertebral disc (see spine disorders in the adult bone and joint section) which may need physiotherapy or surgical correction.