Results from a new study published in the March issue of Obstetrics and Gynaecology demonstrate that the use of depot medroxyprogesterone acetate (DMPA) does not appear to increase fracture risk. Whilst the use of DMPA reduces serum oestrogen levels and is associated with significant loss of bone mineral density (BMD), this study shows that it does not appear to have an effect on fracture risk. In addition although DMPA users had higher fracture risk than non-users, the risk did not increase after starting DMPA but was similar to before it was initiated.
The retrospective cohort study by Lanza et al1 of 312,395 women, who had had 11,822 fractures, was designed to assess the extent to which DMPA increases fracture risk. Using data from the General Practice Research Database, the study compared fracture incidence in DMPA users with women using non-DMPA hormonal contraceptives. It also investigated fracture incidence before and after initiation of contraceptive use. The study reported that before contraceptive use started, DMPA users had a higher fracture risk than non-users (incidence rate ratio [IRR] 1.28; 95% confidence interval [CI] 1.07-1.73). After use began, crude fracture incidence was 9.1/1000 person-years for DMPA users and 7.3 for non-users (crude IRR 1.23; 95% CI 1.16-1.30). Fracture risk in DMPA users did not increase after starting DMPA (IRR after/before 1.08; 95% CI 0.92-1.26). Fracture incidence was 9.4/1000 person years in low exposure DMPA users, and 7.8/1000 in high-exposure DMPA users. DMPA users had a higher fracture risk than non-users at the start of contraceptive use, with no discernable induction period.
Commenting on the results Professor Anna Glasier, Honorary Professor of the University of Edinburgh and the London School of Hygiene and Tropical Medicine, said “This study confirms what others have shown, that women who use Depo-Provera® appear to have a modest increase in fracture risk compared with women using other contraceptive methods. Importantly however, in this UK population the increased risk of fracture preceded the start of Depo-Provera®. The difference in fracture risk was mainly in fractures associated with trauma rather than those typical of osteoporosis. Further research is indicated to explore behavioural differences among populations of women choosing to use different contraceptive methods.”
1. Lanza L. et al. Use of depot medroxyprogesterone acetate contraception and incidence of bone fracture. Obs and Gynae. 2013; 121(3):593–600.