Menstrual and reproductive factors and hip fractures in post menopausal women

Objectives: We analyzed the relationship between menstrual and reproductive history and risk of hip fractures in post-menopausal women using data from an Italian case-control study. Methods: Cases were 206 post-menopausal women admitted for fractures of the hip/proximal femur to a network of teaching and general hospitals in Milan, Italy. The comparison group consisted of 590 post-menopausal women admitted to the same network of hospitals for acute, non-neoplastic, non-hormone-related conditions, other than traumatic or orthopedic disorders. Odds ratios (OR) of hip fracture were derived from unconditional multiple logistic regression. Results: No relation emerged between risk of hip fractures and age at menarche, lifelong menstrual cycle pattern and age at menopause. In comparison with women with age at menopause greater than or equal to 53 years, the multivariate OR of hip fractures were 1.2, 1.1, 1.2 and 0.5 in women with menopause at 50-52, 45-49, 40-44 and before 40 years (X(1)(2) trend 0.21). In comparison with nulliparae, the estimated age-adjusted OR was 0.6 (95% confidence interval, CI, 0.4-0.9) for parous women, but the multivariate estimate was not significant (OR 0.8, 95% CI 0.6-1.3) and the multivariate trend in risk with number of births was not significant either. No relation emerged between hip fractures and age at first and last birth, and history of abortions. Conclusions: This study found no relevant influence of menstrual and reproductive factors on the risk of hip fractures in post-menopausal women. However, this is not in contrast with the observation of a short-term effect of menopause and, more in general, female hormone levels on osteoporosis and hence on hip fractures.