1. University of Utah, Salt Lake City, Utah
2. The George Washington University Biostatistics Center, Washington, District of Columbia
3. Drexel University, Philadelphia, Pennsylvania
4. Wayne State University, Detroit, Michigan
5. Departments of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois
6. Departments of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
7. Departments of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas
8. Departments of Obstetrics and Gynecology, Wake Forest University Health Sciences, Winston-Salem, North Carolina
9. Departments of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
10. Columbia University, New York, New York
11. Departments of Obstetrics and Gynecology, Case Western Reserve University-MetroHealth Medical Center, Cleveland, Ohio
12. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
13. University of Miami, Miami, Florida
14. The University of Texas Health Science Center at Houston, Houston, Texas
15. Departments of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
16. University of Alabama at Birmingham, Birmingham, Alabama
17. Departments of Obstetrics and Gynecology, University of Tennessee, Memphis, Tennessee
18. Departments of Obstetrics and Gynecology, University of Iowa, Iowa City, Iowa