Congenital abnormalities - epidemiology 2 Congenital abnormalities - prevention and control 2 Developing countries 2 Neural tube defects 2 Public health surveillance 2 World Health Organization 2 Centers for Disease Control and Prevention (U.S.) 1 Centers for Disease Control and prevention 1 Clinical epidemiology 1 Disease Outbreaks 1 Epidemiologic Methods 1 International Clearinghouse for Birth Defects Monitoring System 1 International Clearinghouse for Birth Defects Monitoring Systems 1 Methodology 1