Each month K.C. Esperance, 31, a San Francisco nurse practitioner, suffered menstrual cramps so agonizing that she would take to her bed, curl up and pray that she would live through the next couple of days. Doctor after doctor gave her the same ineffectual advice: rest, take some codeine and bear with it.
During her teens, Maria Menna Perper, 42, a New Jersey biochemist, suffered intestinal problems around the time of her period. By her late 30s, she felt "excruciating, burning pain" in her colon every month "like clockwork." Eventually the pain became continuous, and it was impossible for her to...