1. Department of Obstetrics and Gynecology, Vagelos College of Physicians and Surgeons, Joseph L. Mailman School of Public Health, Columbia University, New York, New York
2. Department of Health Policy and Management, Joseph L. Mailman School of Public Health, Columbia University, New York, New York
3. Department of Obstetrics and Gynecology, Biostatistics Center, The George Washington University, Washington, District of Columbia
4. Department of Obstetrics and Gynecology, University of Cincinnati, Cincinnati, Ohio
5. Department of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
6. Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
7. Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas
8. Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah
9. Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
10. Department of Obstetrics and Gynecology, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio
11. Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois
12. Department of Obstetrics and Gynecology, Children's Memorial Hermann Hospital, The University of Texas Health Science Center at Houston, Houston, Texas
13. Department of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
14. Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
15. Department of Obstetrics and Gynecology, Drexel University, Philadelphia, Pennsylvania
16. Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon
17. Department of Obstetrics and Gynecology, The University of Texas Medical Branch, Galveston, Texas
18. Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan