Down's syndrome in Sweden. An epidemiological study of a three-year material.

Abstract

ABSTRACT. Lindsjö, A. (Department of Drugs, National Board of Health and Welfare, Stnckholm, Sweden). Down's syndrome in Sweden — an epidemiological study of a three‐year material. Acta Paediatr Scand, 63: 571, 1974.—A continuous, exact monitoring of the incidence of congenital chromosomal disorders is of great interest for the study of the possible significance of exogenous agents in the origin of various Chromosome aberrations. An investigation of the incidence of Down's syndrome in Sweden has been carried out covering the years 1968–70. The total incidence (1:755) was found to he lower than in earlier Swedish investigations. This is probably due to a reduction in the mean maternal age at childbirth. The earlier, characteristic bimodal distribution of maternal age at the birth of children with Down's syndrome has now been reversed. The age‐specific incidences showed significantly higher values for the maternal age groups 2629 and more than 40 years in comparison with two earlier extensive surveys from the United Kingdom and Australia. A higher confirmation efficiency due to reports from cytogenetic laboratories may also possibly have contributed to the higher Swedish figures. From 1971 onward, Down's syndrome will be reported to the Swedish register of congenital malformations, so that changes in the incidence can be continuously observed. The investigation demonstrates the difficulty in comparing incidence figures from different time periods of a disease, the origin of which is dependent on maternal age.