1. Division of Neonatal Medicine, Department of Pediatrics, Warren Alpert Medical School, Brown University, Providence, Rhode Island;
2. Department of Pediatrics, Division of Neonatal-Perinatal Medicine,University of Texas Southwestern Medical Center, Dallas, Texas;
3. Division of Statistical and Data Sciences, RTI International, Research Triangle Park, North Carolina;
4. Division of Biostatistics and Epidemiology, RTI International, Rockville, Maryland;
5. Neonatal Research Network, National Institutes of Health and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland; and
6. Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University, Palo Alto, California