Down’s syndrome screening is not a mandatory test, but it is recommended. It is a screening test that is performed between 14 and 20 weeks of gestation to determine the risk of Down’s syndrome in the fetus by measuring the levels of HCG, estriol and methemoglobin in the blood of the pregnant woman, combined with the gestational age and maternal age. Down’s syndrome, also known as trisomy 21, is a chromosomal abnormality. The survival rate of children with Down syndrome is low, and those who survive have significant mental retardation and growth disorders, and may be associated with multiple malformations. There is no effective treatment or prevention method for this disease. Therefore, people of childbearing age should pay attention to pre-pregnancy and pregnancy check-ups, actively improve Down’s syndrome screening, conduct confirmatory tests if abnormalities are detected, and promptly terminate the pregnancy if the fetus develops abnormally. In general, the older the mother is, the higher the risk of Down’s syndrome in her fetus, especially in women aged >35 years. If the test results show a high or critical risk, further non-invasive DNA or amniocentesis tests are required to clarify the diagnosis. In addition, women with Down’s syndrome in their family or who have already given birth to a child with Down’s syndrome are at high risk. If they do not undergo Down’s syndrome screening, they can undergo non-invasive DNA or amniocentesis tests to confirm the diagnosis and terminate the pregnancy.