1. Department of Obstetrics and Gynecology The George Washington University School of Medicine and Health Sciences Washington DC USA
2. The George Washington University School of Medicine and Health Sciences Washington DC USA
3. Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology University of North Carolina School of Medicine Chapel Hill NC USA
4. Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology The George Washington School of Medicine and Health Sciences Washington DC USA