Hormonal contraception and pelvic girdle pain during pregnancy: a population study of 91,721 pregnancies in the Norwegian Mother and Child Cohort.

STUDY QUESTION Is pre-pregnancy hormonal contraception use associated with the development of pelvic girdle pain during pregnancy? SUMMARY ANSWER In contrast to combined oral contraceptive pills, long lifetime exposure to progestin-only contraceptive pills or the use of a progestin intrauterine device during the final year before pregnancy were associated with pelvic girdle pain. WHAT IS ALREADY KNOWN Pelvic girdle pain severely affects many women during pregnancy. Smaller studies have suggested that hormonal contraceptive use is involved in the underlying mechanisms, but evidence is inconclusive. STUDY DESIGN, SIZE, DURATION A population study during the years 1999-2008. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 91,721 pregnancies included in the Norwegian Mother and Child Cohort Study. Data were obtained by two self-administered questionnaires during pregnancy weeks 17 and 30. MAIN RESULTS AND THE ROLE OF CHANCE Pelvic girdle pain was present in 12.9% of women who had used combined oral contraceptive pills during the last pre-pregnancy year, 16.4% of women who had used progestin-only contraceptive pills, 16.7% of women who had progestin injections and 20.7% of women who had used progestin intrauterine devices, compared with 15.3% of women who did not report use of hormonal contraceptives. After adjustment for other study factors, the use of a progestin intrauterine device was the only factor based on the preceding year associated with pelvic girdle pain [adjusted odds ratios (OR) 1.20; 95% confidence interval (CI): 1.11-1.31]. Long lifetime exposure to progestin-only contraceptive pills was also associated with pelvic girdle pain (adjusted OR 1.49; 95% CI: 1.01-2.20). LIMITATIONS, REASONS FOR CAUTION The participation rate was 38.5%. However, a recent study on the potential biases of skewed selection in the Norwegian Mother and Child Cohort Study found the prevalence estimates but not the exposure-outcome associations to be influenced by the selection. WIDER IMPLICATIONS OF THE FINDINGS The results suggest that combined oral contraceptives can be used without fear of developing pelvic girdle pain during pregnancy. However, the influence of progestin intrauterine devices and long-term exposure to progestin-only contraceptive pills requires further study. STUDY FUNDING/COMPETING INTEREST(S) The present study was supported by the Norwegian Research Council. None of the authors has a conflict of interest.