1. Department of Medicine, Brigham and Women's Hospital, Department of Pediatrics, Massachusetts General Hospital, Department of Medicine, Children's Hospital Boston, and Harvard Medical School, Boston, Massachusetts.
2. Division of General Medicine and Primary Care, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
3. Departments of Obstetrics, Gynecology and Reproductive Sciences, and Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
4. Departments of Pediatrics and Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.