Pelvic Girdle Instability causes pelvic pain that is common in pregnancy especially third trimester. It is caused by more than usual movement in the joints of the pelvis. Pelvic pain usually occurs with sideways movements, changing direction, sitting down or standing up, or rolling over in bed.
After 12 weeks gestation the relaxin hormone makes the muscles, ligaments and tendons softer than usual. This means that there is more movement in joints and the fused joints of the pelvis can develop some movement which produces muscle spasm around the joint. In third trimester when the head partly descends into the pelvis there is increased pressure on the bones of the pelvis as well as bladder, bowel, and nerves of the pelvis.
Pelvic girdle instability and pelvic pain can occur all around the pelvis. There can be symphysis pubis pain in the pubic bone at the front, hip pain, groin pain and / or pain in the right and left sacro-iliac joints where the sacral bones of the pelvis are fused to the iliac bones of the pelvis on either side of the lower back. The pressure within the pelvis tries to push the hips away from the pelvis and the groin ligaments have to work harder to stabilise the hip joints. This contributes to the waddle gait of later pregnancy.
Pelvic girdle instability is made worse by carrying something on one side or putting all the weight on one leg. Holding a toddler balanced on one hip is likely to increase pelvic pain. When carrying anything it is important to hold it centrally so that there is equal weight on both legs. When getting out of a bed or a car there is less pressure on the pelvis if the weight is transferred to both legs equally rather than having all the body weight on one leg. If pelvic pain is severe it may be necessary to sit down to put on pants so that there is no standing on one leg involved.
At rest, paracetamol or hot packs may take the edge off the pain. If the hot pack is comfortable on the skin it will not cause any problems for baby. It is helpful to get a good balance between resting and moving around to keep up the stamina.
Physiotherapy may help with pain due to pelvic girdle instability. The physiotherapists can provide elasticised belts which are worn around the pelvis at hip level to decrease movement in the pelvic joints. These pelvic belts may help with mobilising but they can be uncomfortable for sitting and lying. SRC shorts are like firm lycra bicycle pants designed for women to wear in pregnancy to help with pelvic girdle instability as well as varicose veins in the vulva and legs. SRC shorts can be more comfortable for sitting and lying but they are difficult to wear for long periods in hot weather due to excess sweating. A less firm option that may help a little with symptoms is the cylindrical elasticised bandage Tubigrip. Using at a size that fits around the abdomen, the tubigrip can be folded over several times to increase support of abdominal muscles and decrease movement in pelvic joints.