The probability of a critical risk Down’s baby requires further prenatal diagnosis as prescribed by the doctor. Prenatal screening is to screen for the risk of fetal genetic diseases during the pregnancy cycle, including Down’s syndrome and non-invasive prenatal testing technology (non-invasive DNA testing), when the results suggest that the critical risk of trisomy 21, the results of the Down’s syndrome test is unreliable, can not be judged, and need to follow the doctor’s advice for prenatal diagnosis for further clarification and exclusion, you can do non-invasive DNA or amniocentesis. During pregnancy, it is important to follow the doctor’s instructions to have regular checkups and prenatal screening tests at the appropriate gestational weeks, such as NT (fetal nuchal translucency) test in early pregnancy, Down’s syndrome screening and non-invasive DNA test in early and mid-pregnancy, and ultrasound screening for structural malformations of the fetus. Pregnant women with high-risk factors or abnormal screening results undergo prenatal diagnosis to rule out the risk of chromosomal disorders in the fetus.