The Down screening test, known as Down syndrome prenatal screening test, is designed to predict the presence of congenital disorders such as congenital stupidity and neural tube defects in the fetus. Congenital stupidity is also known as Down syndrome, trisomy 21, which is caused by an abnormality of chromosome 21, and the affected children are characterized by growth retardation, backwardness of intelligence, peculiar facial features, and multiple malformations, etc. There is no effective treatment for this disease. The purpose of prenatal screening tests for Down syndrome is to predict whether the fetus is at risk for this disorder. Prenatal screening for Down’s syndrome is performed around 7-13 weeks of pregnancy and 14-20 weeks of pregnancy. If the test results indicate that the fetus is at high risk for Down’s syndrome, amniocentesis or chorionic villus testing will be required to further confirm the diagnosis. Although the Down syndrome prenatal screening test is not 100% accurate, every woman should follow her doctor’s instructions and undergo the test on a regular basis, as a child with congenital stupidity can bring a heavy burden to the family.