In order to avoid giving birth to stupid children, \”Down syndrome screening\” is almost one of the examination items that obstetrics must choose. Once pregnant women are identified as high-risk in the initial examination, invasive tests such as amniocentesis were recommended in the past, but in recent years, \”non-invasive prenatal genetic testing\” has been increasingly recommended. The former requires enduring the pain of flesh and blood, while the latter only requires the extraction of 5 ml of venous blood. However, \”non-invasive prenatal genetic testing\” may not be feasible for some time to come. Recently, the State Food and Drug Administration and the National Health Planning Commission