Objective:Processing of results of birth defects in recorded in children of mothers taking medication during the first trimester of pregnancy (Czech Republic,1996 -2000). Type of study:Retrospective analysis of data from the records of birth defects in the CR. Method:Processing of the incidence of selected types of birth defects found in children born to mothers who took medicines during the first trimester of pregnancy.Data from the nationwide recording of congenital defects kept in the Institute of Health Information and Statistics of the CR in 1996 -2000 were used.From the total number of 686 cases recorded 651 were in born children and 35 in foetuses.Among the affected born infants were 284 girls and 392 boys.In 10 instances the sex was not known.Some birth defects were more frequent than in the general population. Results:The authors recorded in a retrospective analysis covering the years 1996 -2000 a total of 686 with birth defects among the offspring of women taking medication during the first trimester of pregnancy and a total of 961 diagnoses of congenital defects were made. Conclusion:The authors submit results of the incidence of birth defects based on nationwide records of the period 1996 -2000.They analyze types of birth defects in the offspring of women who took medication during the first trimester of pregnancy.The type of drugs will be analyzed after supplementation of data with those for 2001.

        Key words: birth defect,population teratology,teratogen,incidence,Czech Republic