The best time to have a non-invasive means non-invasive DNA test is between 12 and 24 weeks of pregnancy. The non-invasive DNA test is performed by drawing maternal venous blood and extracting free fetal DNA from the blood to screen for fetal chromosomal disorders, mainly trisomy 21, trisomy 18 and trisomy 13. Fetuses with chromosomal abnormalities are combined with a variety of fetal malformations and there is no cure. Therefore, if a chromosomal abnormality is detected during pregnancy, it is best to terminate the pregnancy by induction of labor. Non-invasive screening is less risky and has a high accuracy rate of over 95%. For pregnant women with high or borderline risk of Down’s syndrome, or those who are over 35 years old, non-invasive screening can be performed. If financial conditions allow, it is also possible to skip the Down’s syndrome screening and perform the non-invasive test directly. In addition, non-invasive DNA testing does not require an empty stomach and the results can be available about 2 weeks after the blood is drawn.