1. Department of Obstetrics and Gynecology, Ohio State University, Columbus, Ohio
2. The George Washington University Biostatistics Center, Washington, District of Columbia
3. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois
4. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, MetroHealth Medical Center-Case Western Reserve University, Cleveland, Ohio
5. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University, New York, New York
6. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Utah Health Sciences Center, Salt Lake City, Utah
7. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
8. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
9. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
10. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
11. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
12. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, McGovern Medical School-Children's Memorial Hermann Hospital, Houston, Texas
13. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon