Antioxidant status is related to inflammatory and metabolic stress and is of additional interest in light of a current NIH NICHD study to examine the changes in oxidant stress during the menstrual cycle. The primary parameter we will use is total antioxidant capacity (TOAC). Several other parameters of plasma redox status can be measured if interesting trends are detected. These parameters will also be measured at days 1 and 21 of the respective cycles. We have previously described the antioxidant effects of estrogen and prooxidant effects of progestins and differences among the progestins in in vitro systems.