Chiropractic Management of Pregnancy-Related Low Back Pain
Researchers estimate that between 45-75% of pregnant women will experience low back pain at some stage of their pregnancy. (1-5) Up to 33% rate their pain as severe. (6) Pregnancy-related low back pain (P-LBP) leads to lower quality of life, restricted activity, and disability, with almost 25% of pregnant women taking sick leave for LBP. (2,7-11) The recurrence rate for pregnancy-related low back pain is 85-90%. (11-14) Consequently, almost 1 in 5 women who report P-LBP during an initial pregnancy will avoid future pregnancies due to fear of returning symptoms (15)
Stressors and Postural Strains
Pregnancy-related low back pain is not generally the result of true structural disease, like disc lesion or spondylolisthesis, but rather a combination of “functional” stressors, including weight gain, gait changes, and postural strains that occur contemporaneously with hormone-induced ligamentous laxity. (16-20) Pregnancy creates the perfect firestorm of progressively increasing load with diminishing stability. (21) The average woman gains between 20- 40 pounds throughout pregnancy. (13,22) This predominantly frontal weight gain advances the center of gravity, forcing an anterior pelvic tilt and lumbar hyperlordosis, placing excessive stress on the ligaments, discs, lumbar facet joints and sacroiliac joints. (23-25) Since an excessive lumbar lordosis diminishes the spine’s capacity to absorb axial load, the intervertebral discs undergo excessive compression, likewise exacerbated by weight gain. (26-28) The abdominal muscles, which are an integral support mechanism for the lumbar spine, are stretched to accommodate the expanding uterus, thereby compromising their ability to maintain posture and support. (13) Biomechanical stressors are compounded by the hormone relaxin, which increases tenfold during pregnancy. (13) Relaxin triggers lumbopelvic hypermobility and threatens core stability. (26)
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The extremes of activity seem to contribute to P-LBP. (29,30) Sedentary lifestyles increase the risk of developing low back pain. Unfortunately, regular exercise and physical activity typically decrease throughout pregnancy. (31-38) Conversely, lifestyles and occupations that are “physically demanding” also carry an increased risk of developing pregnancy-related low back pain. (13) A history of lower back pain doubles the risk of developing P-LBP. (13)
Onset of Pain
Pregnancy-related low back pain typically starts between the fifth and seventh months. (39) Nevertheless, a significant proportion of women experience pain in the first trimester before mechanical changes could play a significant etiological role. Early onset pain may be related to hormonal and/or emotional stressors. (13,40)
Symptoms of P-LBP are typically localized to the lumbosacral region but may radiate to the buttock and posterior thigh. Symptoms extending into the calf are possible (41), but should raise suspicion for lumbar radiculopathy. Most patients describe their pain as mild to moderate, but 20-30% report “severe” symptoms. (42,43) Symptoms are often provoked by activity, including standing, sitting, coughing, sneezing, and straining during a bowel movement. (44) Symptoms often increase throughout the day. (23,45-47) Many patients report nighttime pain that disturbs sleep. (23,39) The Oswestry questionnaire can help document functional impairment. The Fear Avoidance Belief Questionnaire (FABQ) may help identify psychological factors that could delay recovery. (48,49)
Red Flags
Clinicians should be cautious to screen for symptoms that suggest a more threatening diagnosis, including fever, chills, bleeding, spotting, unusual discharge, cramping, or sudden onset pelvic pain. (50,51) Other “red flags” include light-headedness, shortness of breath, chest pain, headache, calf pain or swelling, decreased fetal movement, and/or neurologic involvement. (52)
Identify Dysfunction
Since true “structural” etiologies are uncommon, clinical evaluation should focus on identifying dysfunction in otherwise healthy tissue. Sacroiliac joint dysfunction is a common source of P-LBP. No single orthopedic maneuver is diagnostic for sacroiliac joint dysfunction, but collectively the following four tests can have a very high predictive value: SI distraction, Thigh thrust (aka P4), SI compression, and Sacral thrust. (53) The Thigh thrust test may be particularly useful in identifying sacroiliac joint dysfunction in pregnant patients. (54) Sensitivity and specificity for SI involvement during pregnancy approach 90% when three or more SI provocation tests reproduce the patient’s symptoms and directional preference testing fails to centralize the patient’s pain. (53) Other potentially useful SI joint assessments include Gaenslen’s test and Gillett test.
Facet joint irritation and lumbar hypomobility may be assessed via the Long dorsal ligament test (55), static palpation, motion palpation, PA shear test, Spring test, and Kemp’s test. The Active straight leg raise test (ASLR) shows good specificity (88%) and sensitivity (54%) for pregnancy-related low back pain. (56)
Pregnant postures, particularly pelvic anteversion, often generate iliopsoas hypertonicity. (57) Hip flexor length may be assessed via the Seated Thomas test. This test is performed by having the patient sit on the edge of an elevated table with one leg hanging off, knee slightly bent. The clinician applies light pressure to assess the flexibility of the hip flexors. The inability to extend the hip to 90 degrees suggests hip flexor hypertonicity. (23) Clinicians should assess for hip abductor/ gluteus medius weakness.
What to Avoid
Diagnostic procedures that utilize ionizing radiation should be avoided during pregnancy. When imaging is required, clinicians may consider ultrasonography or MRI. (58,59) The use of iodine and contrast agents should be avoided as they may carry the potential for fetal injury. (58,59)
While intentional exposure to ionizing radiation should be avoided during pregnancy, some women are unintentionally exposed before their pregnancy is recognized. According to the American College of Radiology, exposure to a single x-ray procedure would not threaten the well being of a developing pre-embryo, embryo, or fetus. (60) A single diagnostic procedure has no known risk for fetal abnormality, including congenital malformation or mental retardation. (59) Exposure to a single x-ray procedure during pregnancy is not a reason to terminate the pregnancy. (62,63)
Diagnosis
The differential diagnosis for pregnancy-related low back pain includes lumbar segmental joint dysfunction, sacroiliac joint dysfunction, lumbar facet syndrome, lumbosacral sprain/strain, lumbar disc lesion, degeneration, lumbar instability, hip pathology, fracture, infection, neoplasm, and diastasis rectus abdominis. (23)
Less than half of women with pregnancy-related low back pain seek medical care. (13,64-66) Unfortunately, 40% of women who experience pregnancy-related LBP continue to suffer six months post-partum, and 20% report pain three years later. (67)
Treatment
A majority of patients and providers would consider CAM therapy, including manual therapy, for pregnancy-related low back pain. (15) In fact, over 90% of prenatal healthcare providers are willing to recommend non-pharmacologic treatment, including alternative therapies. (68) Common therapies for the management of pregnancy-related low back pain include exercise, manual manipulation, education, acupuncture, and pelvic belts. (12,31-33,55,69-78,112,113) A multi-modal approach that includes patient education, exercise, muscle strengthening, and manual therapy has shown superior outcomes with lower disability compared to standard obstetric care. (32,33)
The goal of manual therapy is to restore normal joint mobility and reduce muscle tension. (55) Manual therapy, including chiropractic manipulation, demonstrates medium to large benefit for the management of pregnancy-related low back pain. (75,110,111) Spinal manipulation is an important component in the management of pregnancy-related low back pain. Almost 75% of women undergoing chiropractic manipulation report significant pain reduction and clinically significant improvements in disability. (51,110) Women who seek chiropractic care throughout pregnancy may have an added benefit of shorter labor times. (79,109) Incidentally, postpartum LBP also responds to spinal manipulation, approximately 10 times greater than watchful waiting. (115)
Muscle tightness may be treated with contract/relax stretching and myofascial release. (80) A “waddling” pregnancy posture includes prolonged hip external rotation, which stresses the piriformis muscle. (81) Gentle myofascial release and stretching exercises may be appropriate for hypertonic iliopsoas and piriformis muscles. (57)
Therapeutic exercise has been shown to significantly reduce pregnancy-related low back pain. (82,83) Specific exercises include pelvic tilts, knee to chest stretches, sciatic nerve floss, hamstring stretches, and Kegel exercises. (13,83) Stability exercises should target the gluteus maximus, gluteus medius, quadratus lumborum, abdominal wall, and intrinsic spine muscles in quadruped or side lying positions. (55,84)
Patients may benefit from continuing aerobic exercise throughout pregnancy. The US Department of Health and Human Services exercise guidelines concerning pregnant patients suggest that healthy women may begin or continue moderate-intensity aerobic exercise for at least 150 minutes per week. Women should not begin vigorous exercise during pregnancy, but those who were pre-conditioned to vigorous exercise may continue. (78) In addition to musculoskeletal benefits, ongoing exercise during pregnancy decreases one’s risk of excessive weight gain, pre-eclampsia, gestational diabetes, and pre-term birth, while improving self-image and pain tolerance. (85-93) In particular, water aerobics (83,94) and yoga (95,96,114) have shown benefit.
Conclusion
Employing therapy modalities during pregnancy is controversial. Continuous or pulsed ultrasound is contraindicated over the low back, abdomen, and uterus during pregnancy, as potentially teratogenic sound waves may pass through amniotic fluid. (97) Clinicians should avoid most forms of electrical stimulation over the low back, pelvis, or abdomen during pregnancy. (97) Unwanted uterine contractions are the primary risk associated with e-stim. (98-101) The effect of electrical current on a developing fetus is uncertain, and clinicians should err on the side of caution when considering the application to distant sites. (97) Clinicians may, however, consider the use of a sensory-level TENS unit to sites remote from the uterus.
TENS has been shown to be safe and beneficial for the treatment of lower back pain during pregnancy with no reported adverse effects on the newborn. (98-100,102,103) The use of low-level laser therapy is contraindicated during pregnancy due to possible light-induced effects on fetal growth and development. (97,104) Application of superficial heat to distant sites is safe, however, clinicians should avoid application of heat to the trunk or full body (i.e. hydrotherapy tank), as the elevation of maternal body temperature is known to cause fetal malformations. (105,106) The application of superficial ice is a safe alternative. (97) The use of thermal or non-thermal forms of short-wave therapy is strongly contraindicated during pregnancy. (97)
Activities of daily living advice would include attempting to minimize the lumbar hyperlordosis, take frequent breaks from sitting or standing, and use of a small footstool to alternate feet when standing. Sleeping with a pillow between the knees in a side-lying posture is often well tolerated. Patients should be counseled on proper footwear. The use of a sacroiliac/pelvic support belt is effective and relieving pregnancy-related low back pain. (107,108) Fear avoidance behaviors may be lessened through reassurance and education. (85) Acetaminophen is generally an acceptable OTC medication; however, aspirin and Ibuprofen are contraindicated. (13)
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