Demographic characteristics of Down´s syndrome in Navarra. Trends of pre and postnatal diagnosis for the period 1991-2009

Abstract

This paper describes the trends of DS between 1991 and 2009 and assesses the preventive impact on the population and the associated socio-demographic changes.

In the absence of a prenatal diagnosis for DS, the change in maternal age from 1991 to 2009 would have caused a 50% increase in births with this disorder. However, the antenatal rate detection of DS increased from 15.8% in 1991-4 to 64.3% in 2006-9, giving rise to a decreasing incidence trend, not statistically significant, during the study period and to a higher mean age of mothers of live births with DS (32.75± 5,02 and 34.8±4,82 years during the first and second periods of the study, respectively). The proportion of young mothers (<35 years) of live births with DS was 66% in 1991-4 and 45% in 2006-9. Close to one fifth of the total population of pregnant women, however, did not want to go through a maternal screening test or amniocentesis. Seventeen per cent of all live births with DS had a positive screening test, but mothers decided to continue with the pregnancy. These results suggest that, despite the application of new and more sensitive screening tests, the incidence of DS may still be relatively high in our population, an important factor to be considered for future antenatal preventive programs and adequate postnatal care.