1. Shriners Hospitals; Department of Pediatrics, University of South Florida School of Medicine;
2. Department of Epidemiology and Biostatistics, College of Public Health, Tampa, Florida 33607;
3. All Kids Count, Task Force for Child Survival and Development, Decatur, Georgia 30030;
4. RAND, Santa Monica, California 90407;
5. Epidemiology Program, Massachusetts Department of Public Health, Boston, Massachusetts 02130;