Effects of Pregnancy on Musculoskeletal System

The hormone relaxin is released from the beginning of the pregnancy which helps enable the pelvis to expand during the birth by increasing the laxity (looseness) in the ligaments around the pelvis. The effects of relaxin, also include increased mobility in joints such as the hips and feet, start to show at 6 weeks, and peak at 12 weeks. The pubic symphysis and sacro-iliac joints are particularly affected and can lead to pelvic and low back pain. Relaxin also has an effect on the other joints in the body, in particular the hip joints, shoulders, and the joints in the feet and ankles. The resultant ligament laxity and hypermobility can be long lasting and can cause pain and altered biomechanics throughout the lower limb and altered spinal alignment.

Pelvic floor – the pelvic floor is affected both during pregnancy and during the birth. It is important to address this post birth, with the help of a physiotherapist to regain normal strength and support for the pelvic contents and to help with continence. Pelvic floor training should start during the pregnancy and continue after the birth, until normal function is achieved.

Visceral issues – there are a number of potential visceral issues (effects on the organs), that begin to occur during pregnancy and can continue post pregnancy. As the foetus grows and the uterus becomes larger, there is increased pressure on the kidneys (which also increase in size during pregnancy), the liver, and stomach, as well as the other organs. This reduces the mobility of the diaphragm, which will affect breathing, digestion, bowel function and this can continue after the baby is born. There is also increased pressure on the bladder. Reduced mobility in the visceral system can cause stiffness and pain in the back; altered alignment in the pelvis and neural symptoms.

Core control and strength – as the abdominal muscles are stretched throughout the pregnancy, there is a loss of tone and strength. It is possible to continue to work on the strength of the abdominal and core muscles throughout pregnancy, under the guidance of a physiotherapist or Pilates teacher, who will take into account the stages of pregnancy. There will also be a normal split in the tendon vertically in the middle of the abdominal muscles (diastasis recti), which means care will need to be taken in the rehabilitation of the abdominal muscles after pregnancy, and the advice of a physiotherapist or Pilates teacher should be followed.

Pelvic and Spinal alignment – Pelvic pain is common during and after pregnancy. This is in part due to increased laxity of the ligaments around the pelvis, in the pubic symphysis and around the sacro-iliac joints (SI joints). It is also due to the position of the pelvis caused by flexibility and strength changes, and the size of the bump. The pelvis can tip anteriorly, which will put additional stress on the SI joints and the pubic symphysis. This will mean the bump is lying slightly more in front of the pelvic rim, rather than on top of it, and will cause increased tightness in the back muscles to support this. Some of the anterior tilt of the pelvis is due to tightness in the quadriceps muscles (the muscles down the front of the thighs) which attach into the front of the pelvis and will tip it forwards. This tightness can be further increased by the pressure of the baby on the femoral nerves as they pass through the pelvis and into the thigh. The femoral nerves are the nerves which innervate the quadriceps muscles and if irritated, can cause increased muscle tone, and tighten the quads further.

Read ‘Other changes to your body during preganancy’, here.

Recommended stretches and advice

?????????????????????????????????????????????????????????????????????????????????Quadriceps stretching is useful to help maintain normal pelvic alignment and minimise postural changes and pain. We recommend the following quads stretch. Please click here for instructions.

Gluteal (Buttock Muscle) Strengthening is useful to strengthen as they stabilise the pelvis and will reduce stress on the ligaments, sacro-iliac joints and pubic symphysis. We recommend the following gluteal strengthening exercises.

Upper back pain – Postural changes, increased laxity in ligaments, greater weight anteriorly due to the baby bump, a larger bust size, and breast feeding will all contribute to upper back pain. It is recommended that attention is paid to posture, both during pregnancy and after the birth. Using a pillow or two to support the baby on your lap when feeding will help to take some pressure off your upper back. A supportive bra will also help to relieve upper back pain.

Pectoral muscles (the muscles across the front of the chest) also get tight due to sitting in a more rounded position. Stretching these will help to maintain posture by helping to prevent rounded shoulders.) This is a useful Pec stretch.

Laxity in ligaments in the feet – Relaxin not only affects the ligaments around the pelvis but can also have a marked effect on the ligaments in the feet, which are also under increased strain due to increased body weight. It is advisable to wear supportive shoes, and wear orthotics if you have been prescribed them, even around the house, especially if your ligaments have become very loose and you can see that your feet are becoming more flat than usual.

?????????????????????????????????????????????????????????????????????????????????The following calf stretches are useful as they will help to keep the calves loose, reducing the likelihood of increased pronation through the feet. It will also help to reduce calf cramps at night.

It is also useful to strengthen the calves with these strengthening exercises, to help support the feet as the ligaments become looser.

Swelling in legs – It is normal to have altered circulation in the lower legs, which can result in swelling in the lower legs and feet. It is advisable to sit with the feet elevated for periods of time daily to help with venous return.

Pain under ribs/ heartburn – It is a normal complaint during pregnancy to experience pain under the ribs and heartburn as the uterus and baby increase in size and begin to push up under the diaphragm. It can help to take the arms overhead to reduce this pressure.

Carpal Tunnel Syndrome – Tingling and numbness in the hand due to swelling in the carpal tunnel which is a bony canal formed by the bones in the wrist (carpal bones) and the ligament running across the back of the wrist. The median nerve passes through the canal which is relatively narrow, and the swelling that occurs with pregnancy can reduce the space in the canal and compress the nerve, resulting in pins and needles in the hands, weakness in the thumb and a dull ache in the hands and arms. Raising the hands and arms, resting them frequently if typing and supporting the hands on a pillow at night can all help to relieve symptoms.