1. Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
2. Women's Health Unit, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts.
3. Department of Obstetrics and Gynecology, Boston Medical Center, Boston, Massachusetts.
4. Department of Medicine, University of California, San Diego, San Diego, California.
5. Institute for Clinical Research and Health Policy Studies, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts.