1. Department of Epidemiology; University of North Carolina at Chapel Hill; Chapel Hill North Carolina
2. National Center on Birth Defects and Developmental Disabilities; Centers for Disease Control and Prevention; Atlanta Georgia
3. North Carolina Birth Defects Monitoring Program; State Center for Health Statistics, North Carolina Division of Public Health; Raleigh North Carolina
4. Department of Maternal and Child Health; University of North Carolina at Chapel Hill; Chapel Hill North Carolina