1. Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
2. Section of General Internal Medicine, Women's Health Unit, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
3. Slone Epidemiology Center at Boston University, Boston, Massachusetts, USA.
4. Department of Health Law, Policy, and Management, Boston University School of Public Health, Boston, Massachusetts, USA.