The role of non-invasive during pregnancy is to check the risk of fetal trisomy 21, trisomy 18, and trisomy 13 and to reduce the production of malformed babies. Non-invasive DNA takes the vein blood of a pregnant woman and sequences the free DNA fragments in the mother’s peripheral plasma using next-generation DNA sequencing technology, from which the genetic information of the fetus is obtained, thus detecting the risk of the fetus suffering from trisomy 21, trisomy 18, and trisomy 13. Non-invasive DNA is significantly more accurate than Down’s screening, but is a bit more expensive. Amniocentesis can make a prenatal diagnosis, but it is an invasive procedure with certain risks and is not suitable for screening. Comparatively speaking, non-invasive DNA takes the vein blood of the pregnant woman, which is a safer procedure. However, if the non-invasive DNA shows a high-risk result, the pregnant woman needs to undergo further amniocentesis.