The association between oral contraceptive use, bone mineral density and fractures in women aged 50-80 years

BACKGROUND: The associations between oral contraceptive (OC) use, bone mineral density (BMD) and the risk of fractures remain controversial. STUDY DESIGN: A cross-sectional study of 491 women aged 50-80 years was performed. We assessed OC use and fractures by questionnaire, and BMD and vertebral deformity by dual-energy x-ray absorptiometry. RESULTS: Ever use of OC was associated with significantly higher BMD at the total body (6%, p<.001) and spine (4%; p=.05) (but not hip) after adjustment for confounders. There was also a significant association between duration of OC use and total body and spine BMD. Use of OCs for 5-10 years was associated with reduced vertebral deformity (adjusted odds ratio 0.46, 95% confidence interval 0.22-0.94). CONCLUSIONS: Oral contraceptive use and duration were associated with higher total body and spine BMD and a consistent reduction in vertebral deformities, although most associations did not reach significance.