1. Department of Obstetrics and Gynecology, The University of Alabama at Birmingham, Birmingham, Alabama
2. Birmingham, Alabama
3. Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, North Carolina
4. Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah
5. Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
6. Department of Maternal Fetal Medicine, Intermountain Medical Center, Murray, Utah
7. Ochsner Health System, New Orleans, Louisiana
8. Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, New York
9. Department of Obstetrics and Gynecology, University of Texas Health Sciences Center at Houston, Houston, Texas
10. Department of Obstetrics and Gyneclogy, University of Mississippi Medical Center, Jackson, Mississippi
11. School of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
12. Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama