Oral contraceptive use and fracture risk around the menopausal transition.

OBJECTIVE:The effect of oral contraceptive (OC) use on risk of fracture remains unclear, and use during later reproductive life may be increasing. To determine the association between OC use during later reproductive life and risk of fracture across the menopausal transition, we conducted a population-based case-control study in a Pacific Northwest HMO, Group Health Cooperative. METHODS:For the January 2008 to March 2013 interval, 1,204 case women aged 45 to 59 years with incident fractures, and 2,275 control women were enrolled. Potential cases with fracture codes in automated data were adjudicated by electronic health record review. Potential control women without fracture codes were selected concurrently, sampling based on age. Participants received a structured study interview. Using logistic regression, associations between OC use and fracture risk were calculated as odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS:Participation was 69% for cases and 64% for controls. The study sample was 82% white; mean age was 54 years. The most common fracture site for cases was the wrist/forearm (32%). Adjusted fracture risk did not differ between cases versus controls for OC use in the 10 years before menopause (OR 0.90, 95% CI 0.74, 1.11); for OC use after age 38 (OR 0.94, 95% CI 0.78, 1.14); for duration of use, or for other OC exposures. CONCLUSIONS:The current study does not show an association between fractures near the menopausal transition and OC use in the decade before menopause or after age 38. For women considering OC use at these times, fracture risk does not seem to be either reduced or-reassuringly-increased.