1. Department of Obstetrics and Gynecology, West Virginia University, Morgantown, West Virginia
2. Department of Obstetrics and Gynecology, Duke University School of Medicine, Durham, North Carolina
3. Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
4. Department of Anesthesiology, Duke University School of Medicine, Durham, North Carolina
5. Department of Obstetrics and Gynecology, Wake Forest University, Winston-Salem, North Carolina