1. Department of Maternal-Fetal Medicine, Carolinas Medical Center, Charlotte, North Carolina
2. Department of Clinical Research, Alere Women's and Children's Health, Atlanta, Georgia
3. College of Charleston, Charleston, South Carolina
4. Department of Obstetrics and Gynecology, University of Texas Medical School at Houston, Houston, Texas
5. Perinatal Diagnostic Center, Baptist Health Lexington, Lexington, Kentucky