Denmark's Down syndrome births cut in half by screening

January 1, 2009

The number of Down syndrome births has dropped by half since Denmark introduced national combined risk assessment.

Since Denmark introduced national combined risk assessment for Down syndrome in 2004, the number of infants born with Down syndrome has dropped by half, according to research published Nov. 27 in BMJ Online First.

Charlotte K. Ekelund, of Copenhagen University Hospital in Copenhagen, Denmark, and colleagues analyzed data from 65,000 pregnancies a year from 2000 through 2007 to find out what changes resulted from screening in 2005 and 2006. Screening, conducted during the first trimester, entailed a risk assessment based on maternal age, nuchal translucency scanning, and a test for serum free human chorionic gonadotrophin and pregnancy-associated plasma protein A.

There was a drop in the number of infants born with Down syndrome each year, from 55 to 65 between 2000 and 2004, to 31 in 2005 and 32 in 2006, and whereas in 2000 there were 7,524 amniocenteses and chorionic villus samplings, by 2006 this had dropped to 3,510, the researchers found. Detection rates for 2005 and 2006 were 86% and 93%, respectively, while the false-positive rates were 3.9% and 3.3%, respectively, the data revealed.

Ekelund CK, JØrgensen FS, Petersen OB, et al. Impact of a new national screening policy for Down's syndrome in Denmark: population based cohort study. BMJ. 2008;337:a2547. doi:10.1136/bmj.a2547.