The effects of depot medroxyprogesterone acetate and intrauterine device use on fracture risk in Danish women

BackgroundDepot medroxyprogesterone acetate (DMPA) use may be associated with an increased risk of fractures; however, nothing is known about the risk associated with intrauterine contraceptive device (IUD) use.Study designCase-control study. All women with a fracture (n=64,548) in the year 2000 in Denmark served as cases. For each case, three age-matched controls were randomly drawn from the general population (n=193,641). Exposure was present or previous DMPA or IUD use (only IUD coated with hormones, not those coated solely with copper). Adjustments were made for confounders.ResultsDMPA use seemed to be associated with an increased risk of fractures [odds ratio (OR)=1.44, 95% confidence interval (CI): 1.01-2.06], while IUD use appeared to be associated with a decreased risk of fractures (OR=0.75, 95% CI: 0.64-0.87).ConclusionDMPA use may cause an increased risk of fracture. However, the fact that use of DMPA is rare in Danish women and the lack of baseline data including smoking status and BMI does not allow causal inferences to be made. Likewise, the seemingly decreased risk of fractures with IUD use is probably not a pharmacological effect but rather the effect of residual confounding related to nonincluded confounders regarding lifestyle.