Prior oral contraception and postmenopausal fracture: A Women's Health Initiative observational cohort study

Objective: To test for the possible association of past oral contraceptive (OC) use and incident fracture after menopause. Design: A prospective cohort of 93,725 postmenopausal women. Setting: Forty Women's Health Initiative (WHI) clinical centers across the United States. Patient(s): Ethnically diverse 93,725 volunteer postmenopausal women, 50 to 79 years old. Intervention(s): None. Main Outcome Measure(s): The main outcome was self-reported incident first fracture assessed prospectively by annual questionnaire. Result(s): The adjusted relative hazard (HR) for fracture among past OC users was 1.07 (95% CI, 1.01-1.15). Among women without any postmenopausal hormone treatment, past OC use for ≤5 years led to an HR of 1.15 (95% CI, 1.04-1.27) and for past OC use >5 years led to an HR of 1.09 (95% CI, 0.97-1.23) compared with never users. Conclusion(s): This study does not support the idea that past OC use protects against later fracture.