Down syndrome screening is an important part of prenatal testing for pregnant women, which estimates the risk of fetal congenital defects by measuring the concentrations of alpha-fetoprotein, chorionic gonadotropin, and free estriol in maternal serum. This test is crucial for early detection of children with Down syndrome, although a negative result does not completely rule out the risk, it is significant for protecting fetal health and family happiness.

The NT value measurement result is 2.6mm, its significance for screening chromosomal abnormalities and congenital heart structural anomalies.