The significance of Down syndrome screening Down syndrome is a congenital developmental disorder caused by chromosomal abnormalities. Patients are often accompanied by slow intellectual development, congenital heart disease, eye malformations and other problems. The purpose of Down\’s syndrome screening is to detect the fetus during pregnancy. If the fetus is diagnosed with Down\’s syndrome, parents can choose to have abortion or receive pre-pregnancy genetic diagnosis. Therefore, Down syndrome screening is of great significance to health care during pregnancy. The testing time for Down syndrome screening The best testing time for Down syndrome screening during pregnancy