1. Women's Health Unit, Section of General Internal Medicine, Evans Department of Medicine, Boston Medical Center, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, USA.
2. Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
3. Section of Hematology/Oncology, Boston Medical Center, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, USA.
4. Department of Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, USA.
5. Department of Obstetrics and Gynecology, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, USA.