Changes to the musculoskeletal system which occur during this time include; changes in posture, spinal or pelvic pain as well as lengthening of the abdominal and pelvic floor muscles. The incidence of some degree of back pain during pregnancy is relatively high. Researchers worldwide have suggested it may be between 30 - 70%. The cause of back pain during pregnancy remains debateable and often there are several structures involved. An increase in body weight, hormonal changes, postural changes, a past history of back pain, repetitive bending and lifting are all thought to contribute. The most common sites of pregnancy related back pain are the lower back and the posterior pelvis (back of the pelvis), although other sites may also exist. Postural Changes Changes in the females postural alignment is a natural occurrence as pregnancy develops. The ideal posture ensures the most efficient use of our back muscles so that the least energy is required of these postural muscles. Pregnancy results in an increase in overall body mass and a change in the centre of gravity. As the pregnancy progresses the posture adapts to the changing weight and subsequent forces imposed on the body. The exact postural changes that occur in response to this remain debateable, however the general consensus is that there is an exaggeration of the curve in the lumbar spine (lower back). Hormonal Changes Hormonal changes that occur during pregnancy cause softening of ligaments and the joints, particularly of the pelvis, to enable the foetus to pass through the birth canal more easily. This results in increased joint looseness and decreased stability. This in conjunction with lengthening of the abdominal muscles compromises the stability of the spine and results in excess mobility of the joints. This may be the cause of pain in the lower back and posterior pelvis. Various forms of corsets and supportive braces are available which may provide an increase in joint stability and alleviate low back and posterior pelvic pain. Keeping Fit Despite these natural occurring changes, undertaking physical activity and maintaining a good level of physical fitness is likely to reduce the risk of developing back pain during pregnancy. Health care providers can help you identify and manage any back or pelvic pain during the pregnancy. This may include antenatal classes, yoga or consultation with a physiotherapist or other health care professional.