1. Department of Obstetrics and Gynecology Duke University School of Medicine Durham North Carolina USA
2. Section of Cardiovascular Medicine, Department of Internal Medicine Yale School of Medicine New Haven Connecticut USA
3. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology Duke University Medical Center Durham North Carolina USA
4. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology The Southeast Permanente Medical Group Atlanta Georgia USA