1. Department of Obstetrics and Gynecology, Duke University Health System, Durham, North Carolina
2. Department of Obstetrics and Gynecology, Washington State University Elson S. Floyd School of Medicine, Spokane, Washington
3. Division of Women and Community Population Health, Department of Obstetrics and Gynecology, Duke University Health System, Durham, North Carolina
4. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Health System, Durham, North Carolina