1. Department of Epidemiology, Rollins School of Public Health Emory University Atlanta Georgia USA
2. Department of Epidemiology, College of Public Health University of Iowa Iowa City Iowa
3. Department of Biostatistics, College of Public Health University of Iowa Iowa City Iowa
4. Division of Medical Genetics and Genomics, Stead Family Department of Pediatrics University of Iowa Hospitals and Clinics Iowa City Iowa USA
5. Center for Birth Defects Research and Prevention Massachusetts Department of Public Health Boston Massachusetts USA
6. Birth Defects Registry New York State Department of Health Albany New York USA
7. Departments of Pediatrics, Obstetrics and Gynecology, and Epidemiology, College of Public Health and Health Professions University of Florida College of Medicine Gainesville Florida USA
8. Department of Pediatrics Stanford University School of Medicine Stanford California USA