JoAnn E. Manson, MD, DrPH, is a professor of medicine and women's health at Harvard Medical School, and chief of the division of preventive medicine at Brigham and Women's Hospital, both in Boston. She is one of the lead investigators for two highly influential studies on women's health—the Harvard Nurses' Health Study and the Women's Health Initiative. Dr. Manson is the author, with Shari Bassuk, ScD, of Hot Flashes, Hormones & Your Health (McGraw-Hill).