1 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, 201 Trent Drive, Durham, NC 27710. Electronic address: jenna.hynes@duke.edu.
2 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, 201 Trent Drive, Durham, NC 27710.
3 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, NC.
4 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC.