1. Department of Obstetrics and Gynecology; University of Alabama at Birmingham; Birmingham AL USA
2. Department of Obstetrics and Gynecology; University of Pittsburgh; Pittsburgh PA USA
3. Department of Obstetrics and Gynecology; The George Washington University Biostatistics Center; Washington DC USA
4. Department of Obstetrics and Gynecology; Southwestern Medical Center; University of Texas; Dallas TX USA
5. Department of Obstetrics and Gynecology; University of Cincinnati; Cincinnati OH USA
6. Department of Obstetrics and Gynecology; Columbia University; New York NY USA
7. Department of Obstetrics and Gynecology; University of North Carolina at Chapel Hill; Chapel Hill NC USA
8. Department of Obstetrics and Gynecology; Case Western Reserve University-MetroHealth Medical Center; Cleveland OH USA
9. Department of Obstetrics and Gynecology; Northwestern University; Chicago IL USA
10. Department of Obstetrics and Gynecology; The Ohio State University; Columbus OH USA
11. Department of Obstetrics and Gynecology; Drexel University; Philadelphia PA USA
12. Department of Obstetrics and Gynecology; Wake Forest University Health Sciences; Winston-Salem NC USA
13. Department of Obstetrics and Gynecology; University of Texas Medical Branch; Galveston TX USA
14. Department of Obstetrics and Gynecology; Wayne State University; Detroit MI USA