Abstract
Background Many women have low back pain (LBP) or pelvic girdle pain (PGP) during pregnancy, but there is limited evidence of effective primary and secondary preventive strategies.
Objective The purpose of this study was to investigate whether a group-based exercise program can reduce the prevalence and severity of LBP and PGP in pregnant women.
Design An observer-blinded randomized controlled trial with equal assignments to a training group and a control group was conducted.
Setting The study was conducted in primary care maternity units in 2 suburban municipalities in the southeastern part of Norway.
Patients The participants were 257 pregnant women who were healthy and between 18 and 40 years of age before gestation week 20.
Intervention The training group received supervised exercises in groups once a week, and the control group received standard care.
Measurements The main outcome measures were self-reported LBP and self-reported PGP. Secondary outcome measures were pain intensity in the morning and evening, disability, and 8-Item Short-Form Health Survey (SF-8) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores. Follow-up measurements were performed at gestation weeks 24, 28, 32, and 36.
Results Overall, there was no effect of the program on the prevalence of PGP (odds ratio=1.03, 95% confidence interval [CI]=0.66 to 1.59) or LBP (odds ratio=0.77, 95% CI=0.50 to 1.19). For the secondary outcomes, the estimated mean differences between the groups were −0.4 (95% CI=−0.8 to 0.1) for pain intensity in the morning, −0.4 (95% CI=−1.0 to 0.2) for pain intensity in the evening, −1.0 (95% CI=−2.2 to 0.0) for disability, 1.8 (95% CI=0.0 to 3.7) for the SF-8 PCS, and −0.6 (95% CI=−2.2 to 1.4) for the SF-8 MCS.
Limitations Due to low statistical power, the estimates for the primary outcomes are imprecise.
Conclusions Supervised group exercise did not reduce the prevalence of LBP or PGP in pregnancy.
Low back pain (LBP) and pelvic girdle pain (PGP) are widespread problems of pregnancy, and, when not differentiated, are commonly labeled “lumbopelvic pain.” Pregnancy-related lumbopelvic pain accounts for the majority of sick leave among pregnant women in Scandinavian countries1 and is reported to be a worldwide problem, irrespective of the socioeconomic conditions of the countries.2 It is estimated that 20% to 25% of all pregnant women have lumbopelvic pain sufficiently severe to cause them to seek medical help.3,4 The etiology and pathogenesis of pregnancy-related PGP are unclear and probably multifactorial. The most common hypothesis for the development of PGP is a combination of hormonal and biomechanical factors.4 Motor control patterns in people with PGP have been examined in recent studies, and an alteration in the strategy for lumbopelvic stabilization is suggested to disrupt load transfer through the pelvis.5–9 Abnormal motor control patterns may be a possible mechanism for ongoing pain and disability in patients with PGP,8 as positive changes in motor control have been found to be associated with reductions in pain and disability.10,11
Pain generally increases as pregnancy advances, and it interferes with daily activities. Pregnancy-related lumbopelvic pain is reported to have a negative effect on daily activities such as walking, lifting, climbing stairs, lying flat on the back, turning in bed, housework, exercise, employment, leisure, sexual life, and hobbies and on personal relationships.12 Women with lumbopelvic pain report a significantly lower health-related quality of life than that reported by women who are healthy, and lack of physical ability is found to be a major factor affecting quality of life.11,13
Strategies to manage pregnant women's lumbopelvic pain and disability are varied and include different kinds of treatment modalities. A systematic review of interventions revealed that those who participated in an exercise program in addition to their usual prenatal care, regardless of the program, reported less intense pain than those who received usual care alone, although the extent of the effect was small.14 However, the methodological quality of the studies tended to be rather poor and carried a potential for biased results.14 A recent, thorough literature search identified 3 additional randomized trials; however, no significant positive effect of treatment for pregnant women was shown in these studies.15–17
Knowledge concerning primary and secondary prevention of lumbopelvic pain in pregnancy is scarce.4,14,18 Studies indicate that physical fitness exercises before pregnancy might reduce the risk of developing LBP during pregnancy19,20; however, women with PGP have not been shown to benefit from exercising before pregnancy.19 Exercises appear to be beneficial in patients with LBP, but their role in preventing and diminishing PGP during pregnancy remains uncertain.21–23
To our knowledge, only one previous RCT has focused on primary and secondary prevention of lumbopelvic pain during pregnancy. Mørkved et al24 found that a 12-week, specially designed group training program during pregnancy was effective in reducing the prevalence of lumbopelvic pain in pregnancy. That study, however, did not distinguish between PGP and LBP and investigated the effect only at 36 weeks in pregnancy. Thus, the aim of the current study was to examine whether a supervised, group-based exercise program can reduce the prevalence and severity of LBP and PGP between gestation weeks 20 and 36 of pregnancy.
Materials and Method
Design Overview
This study was designed as an observer-blinded, parallel randomized controlled trial with equal assignment to a group-based exercise program or standard care. All participants gave written informed consent prior to inclusion in the study.
Setting and Participants
Recruitment for the study was conducted between March 2008 and June 2009. The participants were recruited at 2 maternity primary care centers in 2 suburban municipalities (Elverum and Hamar) in the southeastern part of Norway during regular consultations with a midwife. Norwegian-speaking pregnant women who were healthy and aged 18 to 40 years before gestation week 20 were included in the study. Pregnant women giving birth to twins, those with inflammatory rheumatic diseases, and those with high-risk pregnancy identified by the midwife were excluded.
Randomization and Interventions
The participants were enrolled at their maternity care units by the midwife. They received oral and written information and gave their informed consent before the baseline evaluation. The randomization procedure took place after the baseline registrations in blocks of 10. The randomization procedure was computer generated by the statistician (P.M.) not involved in data collection. Group allocation was concealed in consecutively numbered, sealed, opaque envelopes. The participants were informed of group allocation by a telephone call from the primary investigator (M.H.E.) within 1 week after inclusion.
The participants in the training group were referred to 1 of 2 specially trained physical therapists in addition to receiving standard care. They received supervised exercises, including ergonomic advice, in groups and were advised to do home exercises. Each weekly group exercise session lasted 60 minutes, and the groups trained for 16 to 20 weeks (between gestation weeks 16 and 36). The goal of the exercises was to achieve efficient motor control and the ability to dynamically control and stabilize the lumbopelvic region during daily activities. Attention was paid to body awareness, posture, and ergonomic advice in real-life situations (eg, maintaining neutral position of the lumbosacral region while standing, walking, lifting, and bending). The exercises focused on activity of local muscles (eg, pelvic-floor muscles, transversely oriented abdominal muscles), with coordinated activity of global muscles such as the gluteus maximus, oblique abdominal, and hip and thigh muscles. The exercises were intended to avoid inducing pain. Individual guidance was given, and exercises were adjusted by the physical therapist. To ensure that the observer had personal contact and was able to observe each individual's performance of the exercises, a maximum of 8 women participated in each group.
The treatment program consisted of 3 main components: group-based exercises, information, and home exercises. Each group training session started with 20 to 30 minutes of aerobic activity, including stepping, walking, or light jogging on a BOSU* balance ball (Team BOSU, Canton, Ohio), accompanied by varied arm movements. Following the aerobic activity, the women performed knee bends, toe raises, and pelvic floor-muscle contractions in couples. Furthermore, the women performed 4 standardized exercises such as the “birddog,” the “buttock lift,” leaning forward with the arms against a wall or in ropes, and sitting on a Swiss ball with or without the feet on the floor (Appendix).
For all of the exercises, we emphasized maintaining the neutral position of the lumbosacral region. If one exercise provoked pain, an alternative exercise was sought, and attention was paid to relaxed breathing during exercising. Mobilizing and rotational exercises for the lumbar and thoracic lumbar regions also were a part of the exercise session. The training session ended with relaxation and stretching of hip and thigh muscles.
The women received information about normal changes in pregnancy, ergonomic advice, and reminders about the importance of combining physical activity with short breaks and optimal rest. They were further encouraged to perform 3 home exercises daily (Appendix). The first exercise was similar to one of the group exercises. While leaning forward with the arms against a wall, the women were supposed to maintain control of the lumbopelvic region with activation of the pelvic-floor muscles and the transversely oriented abdominal muscles. The second exercise consisted of knee bends to strengthen the thighs while maintaining the lumbosacral region in neutral. The last exercise was a stretching exercise for sustaining muscle length of the external rotators of the hip. Performing the home exercises took approximately 4 minutes to complete, and the women were encouraged to register adherence with the aid of a training diary; however, no data were collected. No charge was incurred for the treatment.
The women in the control group received standard care (regular visits every fourth week at the maternity primary care centers, including information and advice for health complaints provided by the midwife). Both groups were allowed to exercise on their own if they wanted to do so, and treatment was not discontinued during pregnancy.
Outcome Measures
All participants completed questionnaires at baseline (before the 20th week of pregnancy) and at gestation weeks 24, 28, 32, and 36. The questionnaires were distributed and collected by the midwives, who were not aware of group allocations, during the ordinary visits. The main outcome measure was the number of women experiencing LBP or PGP, obtained by yes/no responses to 2 questions: (1) Do you have pelvic girdle pain now? and (2) Do you have low back pain now? Secondary outcome measures were pain and disability, measured with a numerical pain rating scale (NRS) and the Roland-Morris Disability Questionnaire (RMDQ), respectively.26 The NRS rates pain on an 11-point scale (0=“no pain” to 10=“pain as bad as it can be”). The NRS also refers to “worst morning pain during the last week” and “worst evening pain during the last week.” The RMDQ consists of 24 items regarding limitations in different daily life activities, pain, sleep, appetite, and emotional functions due to back pain. The questionnaire was adapted, however, by changing the term “due to low back pain” to “due to pelvic girdle pain/low back pain.” The items are individually scaled from 0 to 1 and totaled as one composite score ranging from 0 (no disability) to 24 (severe disability). In addition, we included the 8-Item Short-form Health Survey (SF-8) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores as secondary outcomes.
Sample Size Calculations
The study was designed to detect a difference of 10% (from 50% to 40%) in the prevalence of PGP or LBP between groups based on 4 repeated measures (gestation weeks 24–36). The α level was set at .05 (type I error), and the β level was set at .3 (type II error). We estimated that group sample sizes of about 116 to 125 would achieve approximately 70% power with 4 repeated measurements having a compound symmetry covariance structure when the proportion from the control group is .17, the correlation between observations on the same individual is at least .50, and the alpha level is .05.
Data Analysis
Results are given as means with standard deviation for continuous variables and as counts with percentages for categorical variables. Generalized estimating equations (GEEs) were applied to assess the influence of covariates on the binary outcomes (ie, LBP and PGP). Absolute risk reductions and number needed to treat with 95% confidence interval (95% CI) were calculated on an Excel spreadsheet (Microsoft Corporation, Redmond, Washington). The results from the GEE analysis are given as odds ratios (ORs) with 95% CI. To assess the validity of the model assumptions, Pearson and deviance residuals were examined together with the dfbeta statistic. For continuous outcomes (ie, morning and evening pain, RMDQ scores, and SF-8 summary scores for the physical and mental components), a mixed-models repeated analysis of variance was applied. Results are given as least squares means with 95% CI. To examine the validity of the normal model, the Cook D and CovRatio statistic for fixed effects and the covariance parameters were examined. In addition, the marginal and conditional residuals were examined. The effects of group and time, the interactions between them, and the covariate “pelvic girdle pain in previous pregnancy” were included in all final models. The analysis was performed using the Statistical Analysis System (SAS, version 9.2, SAS Institute Inc, Cary, North Carolina).
Role of the Funding Source
This work was supported by a research grant from the Norwegian Fund for Post-Graduate Training in Physiotherapy.
Results
Two hundred fifty-seven women were randomly allocated to a training group or to a control group. Thirteen women dropped out of the training group in gestation weeks 24, 28, and 32, and 4 women dropped out of the control group. In addition, 10 women in the training group and 12 women in the control group gave birth in gestation week 36. The flowchart (Figure) shows the details of the study.
Trial profile. *Dropout type I: not related to the trial (eg, change of residence, illness). **Dropout type II: related to the trial (eg, lack of motivation).
The groups were similar at baseline with regard to age, number of children, weeks of pregnancy, civil status, education, back pain in previous pregnancy (Tab. 1), and primary and secondary outcome variables (Tabs. 2 and 3). However, the women in the training group had slightly higher body weight and lower height, resulting in a significantly higher body mass index in the training group compared with the control group. There also was an imbalance between the groups in terms of PGP in a previous pregnancy. Approximately 25% of women in the control group who had children had experienced moderate to severe PGP in a previous pregnancy compared with 46% in the training group.
Background Variables at Baseline in the Training Group and the Control Groupa
Primary Outcomes: Numbers (%) of Participants Reporting Pelvic Girdle Pain and Low Back Pain, Absolute Risk Reduction (ARR) (95% Confidence Interval [CI]), and Odds Ratios (OR) (95% CI)
Secondary Outcomes: Geometric Means (95% Confidence Interval [CI]) or Mean Differences (95% CI)
Primary Outcomes
The main analyses (GEEs) showed no effect of training on prevalence of LBP or PGP. Odds ratios for overall treatment effect accounting for the whole intervention period were 1.03 (95% CI=0.66 to 1.59) for PGP and 0.77 (95% CI=0.50 to 1.19) for LBP. The estimates for the different follow-up time points are shown in Table 2.
Secondary Outcomes
Overall, no significant differences were found in the secondary outcomes. The estimated mean differences between the groups were −0.4 (95% CI=−0.8 to 0.1) for pain intensity in the morning, −0.4 (95% CI=−1.0 to 0.2) for pain intensity in the evening, −1.0 (95% CI=−2.2 to 0.0) for disability, 1.8 (95% CI=0.0 to 3.7) for the SF-8 PCS, and −0.6 (95% CI=−2.2 to 1.4) for the SF-8 MCS. The mean values and estimated differences between the groups in gestation weeks 24 to 36 are shown in Tables 3 and 4.
Eight-Item Short-Form Health Survey (SF-8) Physical Component Summary (PCS) and Mental Component Summary (MCS) Scoresa
Adherence to Exercises and Health Care Use
The median number of supervised exercise sessions among the participants in the training group was 11 (25th–75th percentiles=5.5–14). We do not have any data regarding the participants' adherence to home exercises, but the total amount of exercising did not differ substantially between the 2 groups (Tab. 5). There were no differences between the groups regarding frequency of individual consultations with physical therapists or other health care providers due to PGP or LBP (eTable).
Number (%) of Participants Who Performed Exercises (eg, Aerobics, Swimming, Walking) of at Least 30 Minutes' Duration in the Previous 4 Weeks
Discussion
In this randomized controlled trial, we found no effect of the treatment program on prevalence of self-reported LBP or PGP during pregnancy. Researchers in one previous study concluded that group training during pregnancy was effective for nulliparous women, as pain was prevented in 1 in 8 women during pregnancy.24 Their conclusion, however, was based on one outcome: the presence of lumbopelvic pain once or more times per week. The intensity of lumbopelvic pain is unknown, and the occurrence of some pain once a week might be considered a minor problem. Also, minor differences in disability were found between the groups after the intervention. In light of these findings and previous knowledge, it may be suggested that approaches other than group training might be more effective in reducing lumbopelvic pain in pregnancy.
Furthermore, group exercises might not be optimal in preventing or treating lumbopelvic pain.14 The European guidelines for PGP recommend individualized exercises in pregnancy.4 The exercises in the present study were performed in groups; however, small groups and individual guidance should include individual aspects such as avoiding pain provocation. Supervision of exercises is known to be critically important in improving quality of exercise performance, and a strong correlation has been found between the quality of exercise performance and decrease in pain.27 Even though the exercise groups were small, the individualization of the exercises may not have been adequate.
In the present study, a small tendency toward lower prevalence of LBP was seen in the training group. Patients with PGP are found to be more disabled in terms of higher pain scores and are perceived to be more difficult to treat than patients with pregnancy-related LBP.19,28,29 As exercising before pregnancy seems to reduce the risk of developing LBP but not PGP,19 group exercises during pregnancy might be more suitable in reducing LBP than PGP. It could be argued that the treatment program in the present study was not optimal for PGP. Knowledge about PGP, however, was taken into consideration when designing the exercises (eg, exercises such as a buttock lift may provoke PGP).30 Hence, the women were told to push their feet against a wall to avoid early activation of the hamstring muscles and thereby reduce pain provocation during the buttock lift.6
Positive effects of individualized stabilizing exercises for women with PGP during pregnancy have been found.21 However, no studies, to our knowledge, have examined whether an individualized exercise program can effectively prevent lumbopelvic pain in pregnancy. Compared with group training, individually coached exercises entail higher costs and the absence of a positive social group environment. Despite the fact that pregnancy is associated with profound anatomical and physiological changes, exercise has minimal risks and confirmed benefits for most women.31 The present study did not demonstrate any harmful or adverse events as a result of exercising. Generally, women with uncomplicated pregnancies should be encouraged to engage in physical activities because of their short-term and long-term benefits.31 The exercise program in the present study did not specifically focus on muscle strengthening or cardiovascular endurance training. A main focus was on motor learning including an educational component and physical exercise for 16 to 20 weeks. This focus might have contributed to positive effects postpartum and will be examined in a follow-up study.
There are some strengths and limitations to be considered when interpreting the results of the present study. The strengths include low dropout rates, acceptable adherence, regular measurement points during pregnancy, and the subgrouping of PGP and LBP. The dropouts were not related to complications or negative side effects due to treatment, and the women participated in more than half of the training sessions. Considering that many of the women were multiparous, adherence was regarded as acceptable. Multiparous women and women with PGP have been found less likely to exercise regularly compared with primiparous women.32 A higher frequency of exercising might have influenced the results. Few studies have examined how LBP and PGP fluctuate during pregnancy. One previous study, however, showed a higher prevalence of PGP than LBP during pregnancy.19 In that study, the differentiation between LBP and PGP was based on clinical examination and not only on self-reporting as in the present study, which may reflect an insufficient classification of subgroups. Even though recommendations for classification of PGP exist, there is no international agreement on how to differentiate PGP from LBP.4,33 In previous studies of women with lumbopelvic pain, the women, to a large extent, were able to validate their pain location on a pain drawing.11,28
Another limitation of the study is that the exact number of pregnant women eligible for participation was not registered. However, with the knowledge of the total number of births in the 2 municipalities at the time of inclusion, we can conclude that about 50% were included in the present trial. We also registered the trial after the inclusion was completed, which might leave room for post hoc decisions. The assumptions for the sample size calculations might look post hoc. Based on a pragmatic approach, taking into consideration the available resources and what we expected to be a clinically relevant difference (a 10% decrease in prevalence), we decided to choose 70% power, which increased the probability of type 2 error. When we, in retrospect, consider the results of this trial, we cannot exclude that a type II error had occurred. For example, for the prevalence of LBP, the 95% CI included an OR of 0.50, which is a considerable beneficial effect. The fact that we included both women with and without PGP and LBP can be considered a concern. Based on clinical experience, we designed a pragmatic trial that was intended to prevent development of LBP and PGP among those who did not report such problems by inclusion (about 80% of the participants) and to reduce the negative consequences (pain and disability) of those who had or developed LBP or PGP. Finally, we did not systematically measure unintended or negative effects of the exercise program, which might be considered a limitation.
The findings of this study can be generalized and applied to similar groups of pregnant women. Group exercising in pregnancy can be recommended for general health benefits, but not for reducing lumbopelvic pain. It may well be that future trials should focus on pregnant women with PGP in a previous pregnancy and investigate whether individualized physical therapy is beneficial for this particular subgroup of pregnant women.
Conclusion
We found that this group exercise program with supervised exercises once a week, ergonomic advice, and advice to do home exercises had only a minor influence on the prevalence and severity of LBP and PGP in pregnancy.
The Bottom Line
What do we already know about this topic?
Low back pain and pelvic girdle pain are widespread problems of pregnancy, but knowledge concerning primary and secondary prevention is scarce.
What new information does this study offer?
Supervised group exercise and ergonomic advice did not reduce the prevalence or severity of low back pain or pelvic girdle pain in a group of pregnant women.
If you're a patient or a caregiver, what might these findings mean for you?
Group exercise in pregnancy can be recommended for its general health benefits, but not for preventing lumbopelvic pain.
Appendix.
Standard and Home Exercises
Footnotes
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All authors provided concept/idea/research design. Ms Eggen, Dr Stuge, Mr Mowinckel, and Dr Hagen provided writing. Ms Eggen provided data collection and clerical support. Dr Stuge, Mr Mowinckel, and Dr Hagen provided data analysis. Ms Eggen and Dr Hagen provided project management and fund procurement. Ms Eggen and Ms Jensen provided participants. Ms Eggen, Ms Jensen, and Dr Hagen provided facilities/equipment. Ms Eggen, Mr Mowinckel, and Dr Hagen provided consultation (including review of manuscript before submission).
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The authors thank midwives Åse Rommetveit, Hilde Bangstad, Odny Smistad, Inga-Lill Lygre, and Vera Sæther for their contributions.
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Ethics approval was obtained from the Regional Committee for Medical Research and Ethics in Norway.
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An oral presentation of this work was given at the 7th Interdisciplinary World Congress on Low Back and Pelvic Pain; November 9–12, 2010; Los Angeles, California.
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This work was supported by a research grant from the Norwegian Fund for Post-Graduate Training in Physiotherapy.
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Trial registration: Current Controlled Trials: ISRCTN95014448.
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↵* BOSU is an acronym for “BOth Sides Up,” a reference to the 2 ways a BOSU device can be positioned. The device is used for balance training.25
- Received April 15, 2011.
- Accepted January 20, 2012.
- © 2012 American Physical Therapy Association
References
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