1. Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
2. Department of Obstetrics and Gynecology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
3. Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
4. Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California
5. Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada
6. Department of Obstetrics and Gynecology, University of Chicago, Chicago, Illinois
7. Sunnybrook Research Institute, Toronto, Ontario, Canada
8. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, California
9. Division of Maternal-Fetal Medicine, Duke University Medical Center, Durham, North Carolina
10. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee
11. Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts