1. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
2. Division of General Internal Medicine, University of Washington School of Medicine, Seattle, Washington, USA
3. Magee-Womens Research Institute, Pittsburgh, Pennsylvania, USA
4. Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee-Womens Hospital, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
5. Centers for Disease Control, National Center for Chronic Disease Prevention and Health Promotion, Atlanta, Georgia, USA