1. Health Resources and Services Administration, Maternal and Child Health Bureau, Rockville, Maryland;
2. National Center on Birth Defects and Developmental Disabilities and
3. National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland;
4. Department of Pediatrics, Harvard Medical School, Harvard University and MassGeneral Hospital for Children, Boston, Massachusetts;
5. AJ Drexel Autism Institute, School of Public Health, Drexel University, Philadelphia, Pennsylvania; and
6. Office of the Dean, Milken Institute School of Public Health, George Washington University, Washington, District of Columbia