1. Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington.
2. Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, Minnesota.
3. Department of Pathology, University of Washington School of Medicine, Seattle, Washington.
4. Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle, Washington.
5. Department of Epidemiology and Biostatistics, Indiana University School of Public Health, Bloomington, Indiana.