Estimation of the number of people with Down syndrome in Europe.

We aimed to estimate the nonselective live birth prevalence, actual live birth prevalence, reduction percentage because of selective terminations, and population prevalence for Down syndrome (DS) in European countries. The number of people with DS alive in a country was estimated by first modeling the number of live births of children with DS by year of birth. Subsequently, for these different years of birth, survival curves for people with DS were constructed and then applied to these yearly estimates of live births with DS. For Europe, 2011-2015, we estimate 8,031 annual live births of children with DS, which would have been around 17,331 births annually, absent selective terminations. The estimated reduction of live birth prevalence was, on average, 54%, varying between 0% in Malta and 83% in Spain. As of 2015, we estimate 417,000 people with DS are living in Europe; without elective terminations, there would have been about 572,000 people with DS, which corresponds to a population reduction rate of 27%. Such statistics can be important barometers for prenatal testing trends and resource allocation within countries. Disability awareness initiatives and public policy initiatives can also be better grounded with these more precise estimates.