It is good to do non-invasive DNA. Down’s syndrome screening is to detect the concentration of β-HCG, free estriol and alpha-fetoprotein in the serum of pregnant women, and needs to be combined with clinical information such as the age and weight of the pregnant woman, whether she smokes or not, and whether she suffers from any diseases, to comprehensively calculate the risk of the fetus suffering from trisomy 21, trisomy 13, trisomy 18, and neural tube defects. Non-invasive DNA examines the free DNA of the fetus from the peripheral blood of the pregnant woman for sequencing and analysis to derive the risk of the disease. Non-invasive DNA is highly accurate relative to Down’s screening, with very high detection rates for the common trisomy 21 and trisomy 18 and a low false negative rate. Non-invasive DNA is a prenatal screening rather than a prenatal diagnosis. Genetic counseling and prenatal diagnosis are required for pregnant women with high-risk results. Pregnant women are advised to choose reasonable prenatal screening methods under the guidance of their doctors.