1. Department of Epidemiology; Rollins School of Public Health; Emory University; Atlanta Georgia
2. Oak Ridge Institute for Science and Education; Oak Ridge Tennessee
3. National Center on Birth Defects and Developmental Disabilities; Centers for Disease Control and Prevention; Atlanta Georgia
4. National Center for Immunization and Respiratory Diseases; Centers for Disease Control and Prevention; Atlanta Georgia
5. Department of Epidemiology; School of Public Health; Aarhus University; Aarhus Denmark
6. Department of Obstetrics and Gynecology; Aarhus University Hospital; Aarhus Denmark
7. National Center for Chronic Disease Prevention and Health Promotion; Centers for Disease Control and Prevention; Atlanta Georgia