1. Department of Pediatrics and Doernbecher Neonatal Care Center, Oregon Health and Science University, Portland, Oregon;
2. Department of Neonatology, Beth Israel Deaconess Medical Center, Boston, Massachusetts;
3. Department of Pediatrics, Harvard Medical School, Boston, Massachusetts;
4. Division of Neonatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
5. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; and
6. University of Vermont and Vermont Oxford Network, Burlington, Vermont