The Down screening test is performed by taking a small amount of venous blood from the pregnant woman, separating the serum and then measuring the biochemical indicators in the serum of the pregnant woman, such as detecting AFP, HCG and free estriol in the maternal serum, and taking into account the age of the pregnant woman to determine the risk of Down syndrome in the fetus, as well as screening for trisomy 18 and trisomy 13. If the pregnant woman is older than 35 years old, the Down screening should be supplemented with amniocentesis to further confirm whether the fetus has normal chromosomes. The final report will indicate three types of results: low risk, critical risk and high risk. High risk does not necessarily mean that the fetus has Down’s syndrome, and low risk does not necessarily mean that the fetus is healthy. If you are not sure, you can further determine by fetal chromosome screening and consider whether to continue the pregnancy.