Pregnant women should undergo Down’s syndrome screening between 12 and 16 weeks of pregnancy. Down’s syndrome screening is a comprehensive analysis of the growth and development of the fetus based on the height, weight and gestational week of the pregnant woman by taking her blood serum, which can rule out congenital genetic problems, and can rule out 21-trimester syndrome and 18-trimester syndrome. If the Down’s screening is low risk, it means that the fetus has a small chance of having Down’s syndrome and can be delivered. If Down’s syndrome screening is performed and a critical risk or high risk is identified, attention should be drawn to the need for non-invasive DNA testing or amniocentesis. Because Down’s syndrome screening is only 65% accurate, further testing is needed to make sure the baby is okay before the baby can be born. If there is still a problem with the non-invasive DNA test, amniocentesis is also needed for prenatal diagnosis, which is the final test.