1. Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Houston, Texas, USA
2. Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, Texas, USA
3. National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
4. National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
5. Department of Epidemiology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
6. Dell Pediatric Research Institute, Department of Nutritional Sciences, University of Texas, Austin, Texas, USA
7. Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, Iowa, USA
8. Department of Pediatrics, Stanford School of Medicine, Palo Alto, California, USA