Background: Low back pain (LBP) during pregnancy is very common, affecting between 48- 90% of women. Typically, LBP begins and increases between the fourth and seventh months of pregnancy, and then starts to decrease. It is not fully understood why this happens, but it is postulated that the "rapid weight gain between the fifth and seventh months of pregnancy may exceed the adaptive capability of the trunk musculature in susceptible individuals."Most often, LBP experienced during pregnancy will disappear one to three months postpartum, but this is not always the case. After reviewing many articles, we found that the incidence of LBP varies greatly secondary to the variety of terms used to describe this pain associated with pregnancy. The following are several terms we found related to LBP: pelvic insufficiency, lumbosacral pain, pelvic girdle syndrome, posterior pelvic pain and pregnancy-related pelvic joint pains. In several studies, the prevalence of LBP with sacroiliac pain was approximately 19% in week 30 of gestation, but reached as high as 55% in cases of LBP separate from sacroiliac pain.
Although the cause of pregnancy-related LBP has not been fully determined, there are several theories. During pregnancy, the increase in size of the uterus causes an anterior shift in the center of gravity, which then increases the amount of lordosis in the lumbar spine. As pregnancy progresses, the increasing weight of the uterus forces the muscles of the low back to assume much of the work to maintain an upright posture, since the abdominal muscles and pelvic ligaments are put on stretch. Pregnancy can cause this excessive lordosis, or it may aggravate an already existing lordotic spine. In addition to biomechanical strain from weight gain, there are several other reasons why pain in pregnancy may be experienced: increased spinal loading, pressure from the uterus or fetus, postural changes that cause stress on various structures (Le. posterior ligaments, intervertebral discs, facet joints), postural changes that aggravate preexisting conditions (i.e. stenosis, DJD, spondylolisthesis), and a weakening of the abdominal and pelvic muscles which decrease core stability.
Studies have suggested that exercise during pregnancy may alleviate LBP and decrease the risk of experiencing LBP postpartum. In a recent article in The Physician and Sportsmedicine, author Weiss Kelly reported a number of positive effects of exercise in pregnancy including a reduction in musculoskeletal complaints, an increase in self-image, a decrease in depressive symptoms peripartum, and a healthy decrease in subcutaneous fat deposition. Weiss Kelly went on to state that some studies have shown shorter second stages (active stages) of labor in exercisers, and that exercise may prevent and treat gestational diabetes mellitus via improved glucose tolerance and reduced insulin dependence. Exercise has not been shown to cause increased risk of operative delivery, nor has it been shown to cause increased risk of preterm labor and delivery.
The American College of Obstetricians and Gynecologists (ACOG) recommends exercise in pregnancy. In 1994 the recommendations stated that pregnant women who are healthy can exercise, however, in 2002 the recommendations changed to state that pregnant women who are healthy should exercise. They recommend that women who are pregnant should take part in 30 minutes or more of moderate exercise on most days of the week. Recommendations emphasize that previously inactive women or those with complications should be evaluated before beginning an exercise program, and that physically active women with history of or risk for preterm labor or fetal growth restriction should reduce activity in the second and third trimesters.
Another option that is often recommended for reduction of pregnancy-related low back and/or pelvic pain is use of a pelvic belt, also known as a maternity support binder, intertrochanteric belt, lumbosacral orthosis, or sacroiliac joint (SIJ) belt. A 2002 study by Damen concluded that positioning a pelvic belt below the anterior superior iliac spine significantly reduces SIJ laxity when subjects are positioned in prone. Further research is needed, however, since prone-lying is not a typical position of comfort for pregnant women and because Damen's study design included a small number of subjects, none of whom were actually pregnant.
Clinical Scenario: As physical therapists in an outpatient clinic that focuses on women's health, we wish to determine how best to treat pregnancy-related low back and/or pelvic pain. We have chosen two interventions that are commonly used in practice: pelvic belts and therapeutic exercise. Although pelvic belts have long been recommended, their effectiveness is still being explored. Similarly, exercise is recommended by those in the medical community, but it is unclear if it is an effective treatment for pregnancy-related pain or if there are specific types of exercise that are more beneficial than others. As experts of the musculoskeletal system, physical therapists should be poised and ready to defend the use of pelvic belts and therapeutic exercise in practice, and to know which intervention, if either, works best.
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