Changes in the way research ethics was visualised in the wake of the Nuremberg Trials (1946), led to an atmosphere of protectionism of groups deemed to be vulnerable that was often legislated or regulated. This resulted in the relative underrepresentation of women in clinical trials. The position of women in research was further compromised in 1977, when in response to the tragedies resulting from thalidomide and diethylstilbestrol (DES), the United States Food and Drug Administration (FDA) prohibited women of child-bearing years from participation in early stage clinical trials. In practice this ban was often applied very widely to exclude all women.[151][152] Women, at least those in the child-bearing years, were also deemed unsuitable research subjects due to their fluctuating hormonal levels during the menstrual cycle. However, research has demonstrated significant biological differences between the sexes in rates of susceptibility, symptoms and response to treatment in many major areas of health, including heart disease and some cancers. These exclusions pose a threat to the application of evidence-based medicine to women, and compromise to care offered to both women and men.[6][153]
A related issue is the inclusion of pregnant women in clinical studies. Since other illnesses can exist concurrently with pregnancy, information is needed on the response to and efficacy of interventions during pregnancy, but ethical issues relative to the fetus, make this more complex. This gender bias is partly offset by the iniation of large scale epidemiology studies of women, such as the Nurses' Health Study (1976),[162] Women's Health Initiative[163] and Black Women's Health Study.[164][6]
In addition to diet, exercise and other lifestyle factors can also play an important role in bone health. Smoking and drinking too much alcohol can increase your chances of developing osteoporosis, while weight-bearing exercise (such as walking, dancing, yoga, or lifting weights) can lower your risk. Strength or resistance training—using machines, free weights, elastic bands, or your own body weight—can be especially effective in helping to prevent loss of bone mass as you age. 
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