What is Down\’s screening? Down syndrome screening is a test that uses maternal blood to detect whether a fetus has Down syndrome, usually during pregnancy. Down syndrome is an intellectual disability and physical defect caused by chromosomal abnormalities. Down syndrome screening can detect abnormal amounts of chromosomes, thereby predicting whether the fetus is at risk for chromosomal abnormalities such as Down syndrome. How do Down syndrome screening values differ between men and women? Down syndrome screening predicts the risk of a fetus having Down syndrome by measuring the levels of three special chemicals in the mother\’s blood. These markers are