1 From the Sections of Neonatology (JEF, e-mail: jed.friedman@ucdenver.edu; DJL, present address: Department of Health Outcomes and Policy, College of Medicine, University of Florida, Gainesville, FL) and Nutrition (BEY), Department of Pediatrics, Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine (LAB), Division of Infectious Diseases, Department of Medicine (DNF), University of Colorado Anschutz Medical Campus, Aurora, CO; and the Department of Mathematical and Statistical Sciences, University of Colorado Denver, Denver, CO (SAS).