Risk factors for osteoporosis: A review.

Skeletal fragility and falls are the 2 most potent factors leading to osteoporotic fractures. The aim of this article is to review factors associated with women's risk of developing skeletal fragility and subsequent osteoporosis. Many factors have been implicated, but the evidence for some is unsubstantial. Low premenopausal bone mineral density (BMD), a decrease in BMD, and an increase in bone fragility -- which occur as a result of both aging and the menopause -- are major determinants of subsequent risk for osteoporotic fracture. In addition, low body mass index (BMI), low calcium intake, low physical activity, and smoking can affect BMD. The relative importance of the effects these physical and lifestyle factors have on BMD in midlife women is not fully established. The impact of gynecologic history (parity, lactation, oral contraceptive use, age of menarche) on BMD is uncertain.