Nonpharmacologic Remedies for Back Pain During Pregnancy
During pregnancy, a multitude of new stressors are introduced to the female body as it undergoes physiologic changes. One of the most common complaints is low back pain, which has been reported to affect between 50% and 80% of all pregnant women.1 Additionally, between 10% and 33% of these women experience back pain severe enough to interfere with their daily activities and, at its worst, require prolonged bed rest.2 Despite its prevalence, back pain in this population is severely undertreated because only about 50% of women who experience pain during pregnancy actually seek treatment.3
The etiology of back pain during pregnancy is multifactorial, demonstrating that many evolving physiologic systems contribute to this condition. The management of back pain in this population is obviously very different from the management of back pain in non-pregnant patients, yet physicians need not be apprehensive about treating pregnant women because of concerns about interfering with the pregnancy or harming the fetus. There are a number of safe and effective options available that providers can recommend for these patients.
To best understand the options available to treat back pain during pregnancy, it is important to review some of the postural and hormonal physiologic changes that may be contributing factors. As the pregnancy advances, the increasing weight of the gravid uterus and breast tissue cause a woman’s center of gravity to be displaced anteriorly. To compensate, the head and upper body shift posteriorly over the pelvis, introducing a hyperlordosis of the lumbar spine.4 It is thought that this weight shift causes stress on the intervertebral joints, facet joints, and ligaments, stimulating inflammation of these joints and leading to back pain in the lumbar spine.5 Mogren et al reported that the average onset of back pain was 22.1 weeks into the pregnancy—approximately the fifth or sixth month.1 This is expected because the enlarging abdomen becomes large enough at this time to trigger these compensatory musculoskeletal changes.
The abdominal musculature strength cannot be ignored when considering its role in the development of back pain in this population. The sheer volume and weight of the enlarging uterus place increased stress on the abdominal wall to support it. Eventually, the abdominal muscles weaken as they are stretched to capacity and can no longer support the weight of the fetus, forcing the lumbar musculature to assume additional responsibility in maintaining stability.6
It is not only postural changes that are at the root of back pain. Because some women begin to experience low back pain during their first trimester, when biomechanical changes have not yet occurred, there must be another physiologic factor that results in pain.1 Early studies have pointed to a 10-fold increase in the serum levels of relaxin, a polypeptide hormone released by the corpus luteum, as a potential cause for back pain.3,7 In fact, there appears to be a direct correlation between the level of serum relaxin and the severity of one’s back pain.8
The primary target in the body on which the relaxin hormone exerts its effects is connective tissue; it stimulates collagen turnover by upregulating the production of collagenase enzymes and by modulating collagen synthesis at the cellular level of the fibroblast.9 This state of continuous collagen remodeling may have profound effects on the entire musculoskeletal system, most notably the pelvic girdle.10 For example, it triggers systemic laxity of the joints and decreased tensile strength of the ligaments, both of which lead to increased range of joint motion.11 Lumbar muscles increase in tone to counteract the weakening of the pelvic girdle, causing stiffness and pain in this region. Although these changes are necessary to accommodate the growing fetus and allow for delivery, the low back bears most of the responsibility of compensating for them.10
There are many pharmacologic treatments for back pain in non-pregnant women; however, the risk of harming the fetus precludes the use of drugs other than acetaminophen, which is quite safe and is the drug of choice to treat pain during pregnancy. Despite this, there are still a number of nonpharmacologic treatments a physician can offer that are both effective and safe for mother and child, many of which can be done in one’s own home. Most treatments center on maintaining good posture and directly strengthening weakened muscles, but some use the body’s own physiology to restore and maintain an equilibrium typically lacking during the dynamic period of pregnancy.
Exercise Brings Relief
With regard to relieving or preventing back pain in the pregnant patient, it is essential to attain and maintain proper posture, secondary to increased muscle tone. Preventive measures are best because treatment for back pain late into pregnancy tends to be less successful.3 In addition, women who are more physically fit prepartum experience less back pain during pregnancy.12 That is not to say that women who are physically unfit prior to pregnancy are completely helpless; according to one study, patients who began an individualized training program before or early in pregnancy experienced less overall back pain than those who did not.13 Included in this training program were simple exercises that targeted potentially weakened muscles to lessen the compensatory burden of the lumbar spine. These exercise regimens do not have to be onerous or time consuming; one study showed that one can achieve lumbar pain relief in only 45 minutes of exercise per week.14
Two exercises that every pregnant woman can easily work into her exercise regimen are the pelvic tilt and Kegel exercises. The pelvic tilt can be performed seated, standing, or on all fours and improves posture and eases tension on the low back by strengthening the abdominal muscles. Kegel exercises, easily performed by contracting the muscles that would stop the flow of urine during urination, are important in strengthening the weakened muscles of the pelvic floor. The reinforced pelvic floor provides necessary support for the enlarging abdomen. Kegel exercises may have the additional benefit of relieving urinary incontinence, a common complaint of many pregnant women. Of course, there are countless other exercises women can do for back pain relief; a pamphlet released by the American Congress of Obstetricians and Gynecologists illustrates some examples (see Figures, page 53-55).15