The incidence of Down's syndrome and progress towards its reduction

Publisher Website
Google Scholar
Abstract
Down's syndrome is the most common autosomal aberration and single cause of mental retardation in man. There is a close relation between advanced maternal age and Down's syndrome. The limitation of family size has made a considerable impact on the incidence of Down's syndrome. In Denmark in the 1950s, 50% of Down's syndrome cases were born to mothers over the age of 35. The percentage went down to 25% in the 1970s and was reduced by prenatal diagnosis to 8% in the 1980s. For the period 1980-85 we followed the birth prevalence closely for the different maternal age groups. The birth prevalence was lowered for the age group over 35, but there was a steady rise for the age groups below 35. Early diagnosis, high rate of survival of light-for-date babies and babies with congenital heart defect, and, possibly, exogenous factors working on gametogenesis might be an explanation. To achieve a reduction in incidence, maternal $\alpha$-fetoprotein (AFP)-serum screening for low values may be a possibility. So far, avoidance, but not primary prevention, of Down's syndrome is available.