1. Department of Family and Community Medicine, Penn State College of Medicine, Hershey, Pennsylvania
2. Department of Obstetrics and Gynecology, Penn State College of Medicine, Hershey, Pennsylvania
3. Department of Public Health Sciences, Penn State College of Medicine, Hershey, Pennsylvania
4. Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
5. Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, Pennsylvania
6. Department of Obstetrics and Gynecology, University of Colorado, Denver, Colorado
7. Department of Obstetrics and Gynecology, University of Vermont, Burlington, Vermont
8. Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan
9. Department of Obstetrics and Gynecology, University of California at San Francisco, San Francisco, California
10. Department of Obstetrics and Gynecology University of Oklahoma, Oklahoma City, Oklahoma
11. Department of Obstetrics and Gynecology, University of Texas at San Antonio, San Antonio, Texas
12. Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California
13. Department of Obstetrics and Gynecology, Carolinas Medical Center, Charlotte, North Carolina
14. Department of Biostatistics, Yale University, New Haven, Connecticut
15. Infertility and Fertility Branch, National Institute of Child Health and Human Development, Rockville, Maryland