Bone changes and fracture related to menstrual cycles and ovulation

Women's menstrual cycles and bone remodeling are linked in part by their co-dependency on the stress- and resource-associated variables that govern both of their cyclical natures. Therefore, it is not surprising that evolution has resulted in the same signaling molecules and pathways that regulate normal ovarian function to be involved in bone remodeling and turnover. This review will first provide an overview of the normal menstrual cycle, its modification by age and ovulatory disturbances, and how it parallels bone remodeling. Epidemiological and clinical evidence will be presented that link bone remodeling, strength, and fractures with women's history of reproductive and menstrual cycle characteristics. This combined evidence will then be presented alongside a synthesis of current concepts derived from basic science investigations focused on understanding the molecular mechanisms underlying the influence of ovarian factors on bone physiology. Osteoporosis is a significant source of morbidity for older women. The data presented in this review suggest that a woman's reproductive cycle and ovulatory characteristics foreshadow the future health of her bones. More importantly, identifying the key mechanisms underlying reproductive and bone health would not only provide essential preventative strategies, but may also uncover attractive targets for the treatment of osteoporosis.