1. World Health Organization Collaborating Center in Perinatal Care and Health Services Research in Maternal and Child Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Department of Human Resources, State of Georgia, USA
2. Office of Perinatal Epidemiology, Department of Human Resources, State of Georgia, USA
3. Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA