1. Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
2. George Washington University Biostatistics Center, Washington, District of Columbia
3. Brown University, Providence, Rhode Island
4. University of Texas Medical Branch, Galveston, Texas
5. Northwestern University, Chicago, Illinois
6. the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
7. Columbia University, New York, New York
8. University of Utah Health Sciences Center, Salt Lake City, Utah
9. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
10. University of Alabama at Birmingham, Birmingham, Alabama
11. Duke University, Durham, North Carolina
12. University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado
13. Case Western Reserve University, Cleveland, Ohio
14. University of Texas Health Science Center at Houston, Children's Memorial Hermann Hospital, Houston, Texas
15. Stanford University, Stanford, California
16. University of Texas Southwestern Medical Center, Dallas, Texas
17. University of Pennsylvania, Philadelphia, Pennsylvania
18. Department of Obstetrics, Gynecology and Reproductive SciencesUniversity of Pittsburgh, Pittsburgh, Pennsylvania
19. Madigan Army Medical Center, Joint Base Lewis-McChord, Washington, District of Columbia