Objective of study: Presentation of results of recorded birth defects in the Czech Republic in 1999 and comparison with 1990 - 1998. Type of study: Retrospective demographic epidemiological study. Method: Processing of the incidences of selected types of birth defects assessed in children under one year and detected prenatally in the Czech Republic in 1999. Furthermore the authors updated data of the previous period (1990 - 1998). Data from the nationwide records of birth diseases from the Institute of health information and statistics of the Czech Republic were used and data on the prenatal diagnosis from different departments of medical genetics. Results: In 1999 there was further decline of child births in the Czech Republic to the present level of 89 471 liveborn infants. The absolute number of children with an birth defect in 1999 in the CR was 2685, calculated per 100 000 liveborn infants 300.1. Analysis by different diagnoses of birth defects as compared with the previous period a decline of some birth defects was recorded - in particular clefts of the central nervous system (anencephaly, spina bifida and encephalocele), clefts of the abdominal wall (omphalocele and gastroschisis), diaphragmatic hernia and Down’s syndrome. In other conditions there is, on the other hand, as compared with the previous period, a slight increase of registered cases. This applies in particular to some heart diseases, defects of the gastrointestinal tract (stenosis and atresia of the oesophagus, anorectal malformations) and some less important defects (polydactyly, syndactyly). In the group of birth defects where the incidence declined in born children this phenomenon is due to better results of prenatal diagnosis of birth defects. Conclusion: The authors submit up-to-date results of the nationwide recording of birth defects diagnosed pre- and postnatally in the CR in 1999. For comparison data from previous years were used. These data are an integral part of published international reviews which have become the source of information for comparison with the incidence of birth defects in other countries.

        Key words: birth defect, population teratology, incidence, Czech Republic, prenatal diagnosis, secondary prevention, successfulness