1. Newborn Services Division, the George Washington University Hospital, Washington, District of Columbia
2. Department of Neonatology, Cleveland Clinic Children's, Cleveland, Ohio
3. Department of Epidemiology and Biostatistics, Milken Institute School of Public Health, Washington, District of Columbia
4. Department of Health, State of Maryland, Baltimore, Maryland
5. Department of Obstetrics and Gynecology, the George Washington University Hospital, Washington, District of Columbia
6. Division of Neonatology, Children's National Medical Center, Washington, District of Columbia