1. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
2. Department of Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama
3. Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama
4. Division of Neonatology, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama