1. Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah
2. Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
3. Department of Epidemiology and Biostatistics, George Washington University Biostatistics Center, Washington, Disctrict of Columbia
4. Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
5. Department of Obstetrics and Gynecology, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio
6. Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas
7. Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
8. Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
9. Department of Obstetrics and Gynecology, Thomas Jefferson University, Philadelphia, Pennsylvania
10. Department of Obstetrics and Gynecology, Drexel University, Philadelphia, Pennsylvania
11. Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
12. Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
13. Department of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, Houston, Texas
14. Department of Obstetrics and Gynecology, Columbia University, New York, New York
15. Department of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
16. Department of Obstetrics and Gynecology, University of Miami, Miami, Florida
17. Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois
18. Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio, Texas
19. Department of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania