What causes pregnancy related pelvic girdle pain?
Pregnancy related pelvic girdle pain has long been attributed to
- changes that happen to the body and its postural alignment to accommodate a growing fetus in the abdominal cavity
- hormonal changes that relax the body, including the ligaments of the pelvis or pelvic girdle, to prepare for delivery.
While changes in posture and hormones could contribute to pregnancy related pelvic girdle pain there is not a causal relationship (meaning that there is not clear that one causes the other). (Franklin, Marnach, Bjorklund, Aldabe) For example, some people with postural changes may experience severe pelvic girdle pain during pregnancy, while others may have no pain with similar changes in posture.
The known risk factors for pregnancy related pelvic girdle pain include:
- previous low back pain,
- back or pelvic trauma (such as a previous fall),
- a high level of stress, and
- low job satisfaction (Albert).
Pregnancy related pelvic girdle pain is more complicated than just posture and hormones and requires consideration of the physical, emotional, and social changes of the pregnant person.
The pregnant body demonstrates wide variation in posture (alignment) and muscle activation (the way muscles work) in response to changes in body position and the hormone-driven body relaxation (Moore, Biviá-Roig).
Normally the upper body including the rib cage sits above the pelvis. However, in pregnancy, often the abdomen and pelvis will shift forward. This can change how muscles around the abdomen, back and pelvis work together as they try to accommodate for the increasing abdominal mass, that is, the weight of the baby/babies.
The relaxation occurring through the body allows for increased movement of the joints. Increased joint mobility can in turn influence how muscles to help stabilize the back of the pelvis (sacroiliac joint), front of the pelvis (pubic symphysis), bottom of the pelvis (perineum) and side of the hip.
For most pregnant women, the muscles and fascia surrounding the pelvis sufficiently support the relaxed ligaments of the pelvic and pubic joints, maintaining stability during functional tasks such as sitting, standing, walking, rolling in bed etc. The pelvis does not become a wobbly ring of bones in pregnancy and pain is not directly related to strains occurring within the pelvis. This is because all pain is an output of the brain, it is a collection of danger signals from multiple systems of the body. Signals from pelvic muscles and ligaments are sent to the brain for processing, but other information will also influence pain processing. For example, mental stress, lack of sleep, poor general health or a low immune system can all impact on processing of information and whether the brain sees the overall situation as potentially dangerous and therefore painful. (You can read more about pain and the brain here) It is important that all of these components are considered in the evaluation of pregnancy related pelvic girdle pain.
What helps pregnancy related pelvic girdle pain?