1. Biostatistics Center, George Washington University, Washington, District of Columbia
2. University of Cincinnati, Cincinnati, Ohio
3. University of Pittsburgh, Pittsburgh, Pennsylvania
4. University of Alabama at Birmingham, Birmingham, Alabama
5. University of Texas Southwestern Medical Center, Dallas, Texas
6. University of Utah Health Sciences Center, Salt Lake City, Utah
7. Columbia University, New York, New York
8. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
9. Northwestern University, Chicago, Illinois
10. University of Texas Health Science Center at Houston-Children's Memorial Hermann Hospital, Houston, Texas
11. Drexel University, Philadelphia, Pennsylvania
12. Oregon Health & Science University, Portland, Oregon
13. Wayne State University, Detroit, Michigan
14. Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas