Musculoskeletal Pain in Pregnancy

Prevalence and Characteristics

• Musculoskeletal pain is extremely common during pregnancy, with low back pain occurring in up to two-thirds of pregnancies and pelvic girdle pain in nearly 20% of pregnant women, with prevalence peaking in months 6 and 7 of gestation 1, 2, 3
• Pelvic girdle pain (PGP) occurs in nearly 20% of pregnancies and involves pain at the anterior and/or posterior aspects of the pelvic ring 1

Underlying Mechanisms

• Joint laxity: Pregnancy hormones cause reduced ligament rigidity, weakening joint stability and increasing demand on stabilizing muscles 1, 3
• Biomechanical changes: Increased abdominal mass and shifts in the center of gravity create additional load on the musculoskeletal system 1, 3
• Postural adaptations: As pregnancy progresses, changes in posture to accommodate the growing fetus place stress on the spine and supporting structures 4
• Obesity increases risk for musculoskeletal pain due to chronic overloading of connective tissue structures 4

Severity and Impact

• The prevalence of severe LBP/PGP symptoms ranges from 15% to 20% of pregnant women 1
• Severe cases of pregnancy-related musculoskeletal pain can lead to sleep disturbances affecting maternal well-being 1
• Impaired activities of daily living and functional limitations can occur due to severe musculoskeletal pain 1, 5
• Elevated depression risk is associated with pregnancy-related LBP/PGP 1
• Postpartum weight retention can occur due to activity limitations from LBP/PGP 1
• Delayed resumption of physical activity needed for health maintenance can be a consequence of LBP/PGP 1
• Persistent pain postpartum, especially in women who had both LBP and PGP during pregnancy, is a potential long-term complication 1

Risk Factors

• Heavy lifting (10-20 kg or 22-44 lb) more than 20 times per week increases the risk of musculoskeletal pain 1, 2
• Obesity increases the risk of musculoskeletal pain due to chronic overloading of connective tissue structures 4

Clinical Course and Prognosis

• For most women, back pain resolves spontaneously after delivery 1
• Women at highest risk for persistent postpartum pain include those who had back pain prior to pregnancy, experienced early onset of symptoms during pregnancy, had higher pain severity during pregnancy, or experienced both LBP and PGP simultaneously 1

Common Pitfalls in Management

• Underreporting: Women often don't report LBP/PGP to their prenatal providers, leading to insufficient clinical attention 1
• Inadequate activity modification: Failing to adjust physical activities, especially heavy lifting, can worsen symptoms 1, 6
• Ignoring persistent symptoms: Persistent pain requires evaluation as it may indicate more serious underlying conditions or risk for chronic postpartum pain 1

Ligamentous Laxity in Pregnancy

Physiological Mechanism

• Pregnancy hormones cause ligamentous laxity that softens and relaxes the pelvic floor ligaments, symphysis pubis, and sacroiliac joints, allowing the rigid bony pelvis to expand slightly and accommodate passage of the fetal head during vaginal delivery, according to The Lancet Global Health 7
• Ligamentous laxity represents a natural evolutionary adaptation that occurs during pregnancy to facilitate childbirth, though it comes at the potential expense of long-term maternal health, as reported by The Lancet Global Health 7

Hormonal Changes

• Pregnancy hormones (primarily relaxin, progesterone, and estrogen) reduce ligament rigidity throughout the body, weakening joint stability, as found by the American Journal of Obstetrics and Gynecology 8

Anatomical Sites of Laxity

• The sacroiliac joints experience softening and increased mobility to allow pelvic ring expansion, according to The Lancet Global Health 9, 7
• Pelvic floor ligaments and musculature relax to facilitate easier passage of the fetal head through the levator hiatus, as reported by The Lancet Global Health 7

Functional Benefits for Delivery

• The combination of symphyseal widening and sacroiliac joint mobility allows the closed bony pelvic compartment to expand slightly, accommodating the fetal head, a finding supported by The Lancet Global Health 7
• Relaxation of pelvic floor musculature and ligaments allows significant stretching of the levator hiatus during fetal descent, according to The Lancet Global Health 7

Trade-offs and Complications

• Softening of the symphysis pubis and sacroiliac joints can lead to persistent symphyseal or pelvic girdle pain postpartum, as reported by The Lancet Global Health 9
• Levator ani muscle injury during delivery, facilitated by ligamentous laxity, increases the risk of symptomatic prolapse, according to The Lancet Global Health 9

Clinical Implications

• Heavy lifting (10-20 kg more than 20 times per week) combined with pregnancy-related ligamentous laxity increases musculoskeletal complications, as found by the American Journal of Obstetrics and Gynecology 8

Treatment for Lower Back Pain in Early Pregnancy

First-Line Treatment: Structured Exercise Program

• The American College of Sports Medicine recommends accumulating at least 150 minutes of moderate-intensity physical activity per week, distributed over a minimum of 3 days, to reduce pain and prevent progression to severe symptoms in pregnant women with early-onset lower back pain 10
• Combining aerobic exercise with resistance training is more effective than aerobic exercise alone for musculoskeletal outcomes in pregnant women with lower back pain, according to the British Journal of Sports Medicine 10
• Moderate-intensity activity is recommended throughout pregnancy, defined by heart rate ranges specific to maternal age, to ensure safety and effectiveness of the exercise program 10
• Lower intensity physical activity still provides benefits, so women unable to meet full recommendations should be encouraged to remain active at any level, as suggested by the British Journal of Sports Medicine 10
• High-intensity physical activity should only occur in monitored environments, as safety data for chronic high-intensity exercise during pregnancy are lacking, according to the British Journal of Sports Medicine 10

Evidence Quality Considerations

• The Canadian guideline provides strong recommendations based on moderate-to-high quality evidence for exercise interventions, including a structured exercise program combining aerobic activity, resistance training, and stretching/yoga, to reduce pain and improve outcomes in pregnant women with lower back pain 10