The goal of the current study is to measure the response to seven days of aspirin administration as it relates to urinary thromboxane levels in pre and post-menopausal women. With this study we will be able to examine the change in UTXB2 comparing the premenopausal to post menopausal women. We will also be able to see if the change in UTXB2 in response to aspirin is affected by hormone levels in the premenopausal women. Lastly this study will provide reference data for more far-reaching studies exploring how global changes in hormonal balance (as seen in pregnancy or menopause) or in the level of inflammation (as seen in aging or with CAD risk factors), affect UTXB2 and platelet hyperreactivity.