DR. ROBERT GREENE is one of the country’ s leading hormone specialists, board certified in ob/gyn and reproductive endocrinology. His practice, the Center for Reproductive Health and Hormone Balance, is in northern California. Visit his website at www.robertgreenemd.com. LAURIE TARKAN is a regular contributor to the "New York Times," an award-winning medical writer with more than twenty years of journalism and writing experience, and the mother of two young children.