1. Department of Pediatrics, University of Arizona, Tucson, Arizona;
2. Departments of Epidemiology and
3. New York State Department of Health, Albany, New York;
4. Pediatrics, University of Iowa, Iowa City, Iowa;
5. Department of Neurology, School of Medicine and Dentistry, University of Rochester, Rochester, New York;
6. Department of Pediatrics, Weill Cornell Medical College, New York City, New York; and
7. Bureau of Environmental and Occupational Epidemiology,
8. Department of Physical Medicine and Rehabilitation, School of Medicine, University of Colorado, Aurora, Colorado