Research Review By Dr. Ceara Higgins©

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Date Posted:

November 2016

Study Title:

Exercise level before pregnancy and engaging in high-impact sports reduce the risk of pelvic girdle pain: a population based cohort study of 39 184 women

Authors:

Owe KM, Bjelland EK, Stuge B, et al.

Author's Affiliations:

Norwegian Institute of Public Health, Oslo; Oslo University Hospital; Akershus University Hospital, Lorenskog, Norway; Karolinska Institute, Stockholm, Sweden; University of Oslo; Norwegian Institute of Public Health, Oslo, Norway

Publication Information:

British Journal of Sports Medicine 2016; 50: 817–822.

Background Information:

Pelvic girdle pain is very common in pregnant women (1) and has been associated with disability, depression, reduced quality of life, and higher rates of sick leave during pregnancy (2). Women with pelvic girdle pain also are less likely to engage in regular physical activity during pregnancy (3). One year after delivery, roughly 2-3% of women report chronic pelvic pain. This study explored the association between exercise levels and types pre-pregnancy and pelvic girdle pain during pregnancy in nulliparous women.

Pertinent Results:

39 184 pregnancies were included, with 10.4% reporting pelvic pain in week 30. The average maternal age was 28.5, 95.4% were married or cohabitating, 69.2% were non-smokers pre-pregnancy, 60.1% had completed college/university, and 29.5% were overweight or obese before pregnancy. The group reporting pelvic pain had higher levels of daily smoking, being overweight or obese, being < 25 years of age, and more commonly reported histories of LBP or depression.

56.5% of women reported an exercise frequency of at least three times per week, with only 7% reporting no exercise before pregnancy. Women without pelvic girdle pain at 30 weeks were more likely to report exercise frequencies of 3-5 times per week and participation in high-impact exercises. When the models were adjusted for pre-pregnancy BMI, maternal age, education, history of LBP and history of depression, it was found that women who exercised 3-5 times weekly before pregnancy had a 14% reduced risk of pelvic girdle pain. This reduction in risk was similar in those engaging primarily in high impact exercise. While the risk of pelvic girdle pain seemed to decrease as exercise frequency increased up to 5 times per week, risk increased when exercise frequency reached ≥ 6 times per week (more is not always better!).

Women who exercise pre-pregnancy are more likely to continue to exercise during their pregnancy, so it is possible that their decrease in pelvic pain may be due to the hypoalgesic effects of aerobic exercise and resistance training that has been shown in healthy, non-pregnant patients, and chronic pain patients (7).

Clinical Application & Conclusions:

Pre-pregnancy exercise frequency of up to five times per week was protective against pelvic girdle pain in this large, population-based cohort study. A non-linear relationship was seen with a more rapid decrease in risk at the lower end of the exercise distribution. Women reporting high-impact exercises pre-pregnancy had the lowest risk of pelvic girdle pain. This information illustrates the importance of encouraging regular exercise in women of childbearing age.

Study Methods:

The Norwegian Institute of Public Health, through the Norwegian Mother and Child Cohort study (MoBa) recruited 90 700 mothers (resulting in 108 000 children) from across Norway between 1999 and 2008 for a prospective, population-based cohort study (4).

Participants were selected based on the following inclusion criteria:
  • Nulliparous women
  • Completed both questionnaires 1 (Q1) at pregnancy week 17 and 2 (Q2) at pregnancy week 30
Exclusion:
  • Multiparous women
  • Women with missing information on leisure time exercise in Q1
  • Women with exercise frequency over 25 per week
  • Women with missing information on the co-variables pre-pregnancy BMI, education, smoking pre-pregnancy, marital status, and/or history of depression
Outcomes included mild or severe, self-reported pelvic girdle pain in the anterior pelvis and/or posterior pelvis bilaterally in pregnancy week 30 (6). Pain locations could be: over the pubic symphysis, over one sacroiliac joint, or over both sacroiliac joints. Through the questionnaire (Q1), participants indicated how often they performed 14 exercises at 3 months pre-pregnancy: strolling, brisk walking, running (jogging or orienteering), bicycling, training in fitness centres, swimming, low impact aerobics, high-impact aerobics, prenatal aerobics, dancing, skiing, ball games, horseback riding, and other. Strolling was categorized as non-exercise and excluded from the overall score. Frequencies were as follows: never (score: 0), 1-3 times per month (score: 0.25), once a week (score: 1.0), twice a week (score: 2.0), and ≥ 3 times per week (score: 3.0). Frequencies from all exercise types were then summarized and recoded into five categories ranging from never to ≥ 6 times per week. Finally, 7 groups were generated: non-exercises (strolling and never), brisk walking, non-weight bearing exercises (cycling and swimming), low impact exercises (prenatal aerobics, low impact aerobics, dancing, cross-country skiing, and fitness training), high-impact exercises (running, jogging, orienteering, ballgames, high-impact aerobics), horseback riding (horseback riding and other), and a mixed exercise group (those who didn’t report a dominant type of exercise).

Covariates and possible confounding factors, including maternal age (years), body mass index (BMI), pre-pregnancy education, marital status, smoking pre-pregnancy, heavy work, history of low back pain (LBP), and history of depression, were assessed. In the end, maternal age (years), BMI, pre-pregnancy education, history of low back pain (LBP), and history of depression were controlled for in the statistical analysis.

Study Strengths / Weaknesses:

Strengths
  • A strict definition of pelvic girdle pain was utilized.
  • Adjusted models were used to account for the effect of sample population demographics, and showed that only maternal age significantly affected the estimates.
  • The use of a population-based, prospective design with a large number of participants and a high follow-up rate allowed for robust data collection.
  • Gathering detailed information about pre-pregnancy exercise allowed the authors to consider the impact of the type of pre-pregnancy exercise rather than just the rate or frequency.
Weaknesses
  • Both pre-pregnancy exercise and pelvic girdle pain were self-reported and pre-pregnancy levels were reported in week 17 of pregnancy and therefore may have been inaccurately recalled.
  • Participating women were older, smoked less, had lower parity and higher education than the general pregnant population (5) and may have affected the prevalence of pelvic girdle pain and exercise.
  • Potential bias due to residual confounding cannot be ruled out.

Additional References:

  1. Vleeming A, Albert HB, Ostgaard HC, et al. European guidelines for the diagnosis and treatment of pelvic girdle pain. Eur Spine J 2008; 17: 794-818.
  2. Dorheim SK, Bjorvatn B, Eberhard-Gran M. Sick leave during pregnancy: a longitudinal study of rates and risk factors in a Norwegian population. BJOG 2013; 120: 521-530.
  3. Gjestland K, Bo K, Owe KM, et al. Do pregnant women follow exercise guidelines? Prevalence data among 3482 women and prediction of low-back pain, pelvic girdle pain and depression. Br J Sports Med 2013; 47: 515-520.
  4. Magnus P, Irgens LM, Haug K, et al. Cohort profile: the Norwegian Mother and Child Cohort Study (MoBa). Int J Epidemiol 2006; 35: 1146-1150.
  5. Nilsen RM, Vollset SE, Gjessing HK, et al. Self-selection and bias in a large prospective pregnancy cohort in Norway. Paediatr Perinat Epidemiol 2009; 23: 597-608.
  6. Albert H, Godskesen M, Westergaard J. Prognosis in four syndromes of pregnancy-related pelvic pain. Acta Obstet Gynecol Scand 2001; 80: 505-510.
  7. Owe KM, Nystad W, Bo K. Correlates of regular exercise during pregnancy: the Norwegian Mother and Child Cohort Study. Scand J Med Sci Sports 2009; 19: 637-645.