Down’s non-invasive usually refers to Down’s non-invasive DNA screening, which can be used to further confirm the risk of the fetus having Down’s syndrome, usually after the first Down’s screening has shown a high risk. Non-invasive DNA screening for Down’s syndrome is available from 10 weeks of pregnancy and is best performed between 12 and 22 weeks of gestation. The first screening test is performed by testing the mother’s blood for alpha-fetoprotein, human chorionic gonadotropin, and free estriol, as well as the mother’s age, weight, and gestational age to determine whether the fetus has congenital dysmorphism or neural tube defects. If the results of prenatal screening for Down’s syndrome show that the fetus is at high risk of Down’s syndrome, further tests such as amniocentesis or non-invasive DNA screening to detect chromosomal abnormalities can be performed under the guidance of a doctor, both with high accuracy. Non-invasive DNA screening is performed by collecting peripheral blood from pregnant women, sequencing free DNA fragments in maternal peripheral plasma using next-generation high-throughput sequencing technology, and performing bioinformatics analysis. Since maternal plasma contains fetal free DNA, it can be analyzed to derive the risk of fetus with trisomy 21, trisomy 18 and trisomy 13. The advantage is that it is non-invasive and has high sensitivity and specificity relative to serum biochemical screening, with a detection rate of more than 99% for singleton trisomy 21 and a low false-positive rate.