Danish Scientists have found that screening of pregnant women in their early pregnancies combined with the maternal blood analyses greatly reduced the number of children born with the Down syndrome in this country.

Besides showing a 50% reduction in the Down syndrome incidence, early prenatal screening showed another benefit, a drop in the number of invasive pre-natal diagnostic procedures from 11% to approx. 6% of pregnancies.

New guidelines for prenatal diagnoses were recommended back in 2004 by the National Board of Health in Denmark. This was restricted to women over the age of 35, however it has also been available to other women too.

Women were offered a few prenatal screening tests, a measurement of nuchal translucency in the fetus by ultrasound that shows the risk of the Down syndrome as well as a blood test to look for a certain combination of serum markers that show an increased risk of a chromosomal abnormality. These screenings need to be taken between 11 to 14 weeks of gestation.

If one of these screenings showed elevated risks, an invasive procedure (chorionic villus sampling or amniocentesis) would be offered to confirm the diagnosis of the Down syndrome.

Comparing data from 2004, 2005, and 2006 with previous years’ data showed a reduction in invasive procedures and the number of children born with Down syndrome at national level. When the researchers investigated the history of children born with the Down syndrome, they found that their mothers had declined the offer of screening, or had taken it up too late in pregnancy.