1. Department of Obstetrics and Gynecology; Columbia University Medical Center; New York NY USA
2. Center for Fetal Medicine and Women's Ultrasound and Department of Obstetrics and Gynecology, David Geffen School of Medicine; University of California; Los Angeles CA USA
3. Division of Maternal Fetal Medicine; University of Rochester Medical Center; Rochester NY USA
4. Department of Obstetrics and Gynecology; Massachusetts General Hospital; Boston MA USA
5. Department of Obstetrics and Gynecology; Brigham and Women's Hospital; Boston MA USA
6. Department of Radiology; Brigham and Women's Hospital; Boston MA USA
7. Department of Obstetrics and Gynecology; Eastern Virginia Medical School; Norfolk VA USA
8. Department of Obstetrics, Gynecology and Reproductive Sciences; Yale School of Medicine; New Haven CT USA
9. Drexel University College of Medicine; Philadelphia PA USA
10. San Francisco Perinatal Associates; San Francisco CA USA
11. Society of Maternal Fetal Medicine; Washington DC USA
12. University of Oklahoma; Oklahoma City OK USA
13. Perinatal Quality Foundation; Oklahoma City OK USA