1. Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina2Division of Pediatric Infectious Diseases, Duke University School of Medicine, Durham, North Carolina
2. Department of Economics, Clemson University, Clemson, South Carolina
3. Division of Neonatology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
4. Division of Neonatal-Perinatal Medicine, The University of North Carolina at Chapel Hill
5. Pediatrix-Obstetrix Center for Research and Education, Sunrise, Florida
6. Division of Pediatric Infectious Diseases, Duke University School of Medicine, Durham, North Carolina