1. Department of Obstetrics and Gynecology, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio
2. Biostatistics Center, George Washington University, Washington, District of Columbia
3. Department of Obstetrics and Gynecology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
4. Department of Obstetrics and Gynecology, Columbia University, New York, New York
5. Department of Obstetrics and Gynecology, University of Utah Health Sciences Center, Salt Lake City, Utah
6. Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
7. Department of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
8. Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
9. Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
10. Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
11. Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
12. Department of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
13. Department of Obstetrics and Gynecology, Children's Memorial Hermann Hospital, University of Texas Health Science Center at Houston, Houston, Texas
14. Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon
15. Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois