Generally speaking, combined serological methods are used to screen for Down syndrome. The process is to draw the peripheral blood of pregnant women and then extract the serum. Pregnant women do not have to fast during this process. During the serum examination, the concentration of alpha-fetoprotein (AFP) and serum chorionic gonadotropin (HCG) in the expectant mother\’s serum will be detected, and \”risk factors\” and the pregnant woman\’s weight will be calculated based on the expected date of delivery, age, and gestational age. This way 60-70% of congenital fools can be detected. To achieve the purpose of \”prophet\”. At the same time, this inspection can also check