1. Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan.
2. Departments of Human and Molecular Genetics, Pediatrics, Obstetrics-Gynecology, Epidemiology, and Community Health, Virginia Commonwealth University, Richmond, Virginia.
3. Office of Research on Women's Health, National Institutes of Health, Bethesda, Maryland.
4. Names and institutions in .