1. Department of Epidemiology Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA
2. Department of Mental Health Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA
3. Department of Pediatrics, School of Medicine University of Colorado and Children's Hospital Colorado Aurora Colorado USA
4. Centers for Disease Control and Prevention, Division of Scientific Education and Professional Development Epidemic Intelligence Service Atlanta Georgia USA
5. National Center on Birth Defects and Developmental Disabilities Centers for Disease Control and Prevention Atlanta Georgia USA
6. Center for Autism and Related Disorders Kennedy Krieger Institute Baltimore Maryland USA
7. AJ Drexel Autism Institute Drexel University Philadelphia Pennsylvania USA
8. College of Health and Human Development Pennsylvania State University Pennsylvania USA
9. Wendy Klag Center for Autism and Developmental Disabilities Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA