Why Do I Have Post-Partum Pelvic Girdle Pain?

Lower back pain after pregnancy: what might be causing it and how can you make the pain go away? The SI joint may be to blame.

The SI Joint May Be to Blame for Post-Partum Pelvic Girdle Pain

The sacroiliac (SI) joints are located between the spine and the hip joints. The SI joints are responsible for absorbing and transferring the large amounts of force that are generated in the spine and lower extremities during physical activities. The SI joints are particularly vulnerable to injury because of their location and their orientation. The SI joints provide the crucial balance between pelvis stability and pelvis mobility.

Post-partum pelvic girdle pain (PPGP) (which may include the SI joint(s)) will resolve in most women within 4 months after giving birth,45 but 20% of women who experience this pain during and immediately after pregnancy report continuing pain two and three years postpartum.46 The underlying causes of PPGP are not well defined, with the explanation most likely being a combination of hormonal, biomechanical, and traumatic factors.47

Pelvis Closeup

Potential Causes of PPGP

Hormonal: Relaxin is a hormone that the body produces in increased amounts during pregnancy. This hormone helps increase the flexibility of the ligaments that support the SI joints. This facilitates the widening of the birth canal that occurs during delivery.

Biomechanical: As pregnancy progresses, some of the core muscles (transverse abdominals and pelvic floor) are stretched due to the increasing size and weight of the fetus. Stretching of these muscles may lead to a decrease in the ability of these muscles to stabilize the pelvic joints

As the fetus grows during pregnancy, the center of gravity shifts forward and remains forward in the post-partum period. This typically results in a forward rotation of the pelvic bones, leading to increased load, decreased functional stability and increased wear and tear of the SI joints.48

Traumatic: 52% of women with pregnancy-related low back and pelvic pain have pelvic floor dysfunction including a change in the firing of the muscles (change of motor control).49 This may be due to direct injury of the pelvic floor muscles or injury to the nerves that innervate the pelvic floor muscles during pregnancy and/or delivery. A biomechanical study by Pel showed increased stability of the SI joints with contraction of the pelvic floor and the transverse abdominal muscles together.50

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