First of all, I would like to introduce you to the word “adaptation”. This word is used all the time in the work of a doctor. What tests and medications a doctor prescribes must be appropriate for the patient’s condition, and this is the indication. Which one should I choose: fetal non-invasive DNA test, common Down’s syndrome screening or amniotic fluid test? The first thing you need to do is to make sure you don’t get confused! Only you and your baby’s comprehensive situation, that is, the “indications” will count! The best plan for you and your baby is the best plan. The indications for prenatal diagnosis (amniotic fluid examination) are: 1. senior pregnant women over 35 years of age. 2.High-risk group after prenatal screening. 3, Pregnant women who have given birth to a child with chromosomal disease. 4.Pregnant women whose fetus is suspected to have chromosomal disorders after prenatal screening. 5.One of the couple is a carrier of chromosomal abnormalities. 6.Pregnant women may be carriers of certain X-linked genetic diseases. 7.Other, such as those who have a history of bad pregnancy and delivery or a history of exposure to special teratogenic factors. Traditional prenatal screening methods mainly use biochemical indicators in the peripheral blood of pregnant women, such as alpha-fetoprotein (AFP), chorionic gonadotropin (hCG) and pregnancy-associated protein (PAPP-A) to determine whether the fetus is at risk of Down syndrome or neural tube abnormalities. However, there are disadvantages such as high false positive rate and positive detection rate. In terms of timing, there are two types of Down’s syndrome screening: early pregnancy (11-13+6 weeks) and middle pregnancy (15-20+6 weeks), and pregnant mothers who are in these two time periods and do not have the indications for prenatal diagnosis mentioned above can choose to have general Down’s syndrome screening. The principle of non-invasive fetal DNA testing is to determine whether the fetus is normal by detecting the amount of fetal DNA in the peripheral blood of the pregnant woman, such as prenatal screening for Down syndrome, trisomy 18, trisomy 13, etc. Non-invasive fetal DNA testing has a higher detection rate and a low false positive rate than traditional Down’s screening; it allows most Down’s fetuses not to be missed, while reducing the amount of amniocentesis performed. Non-invasive DNA screening can be performed between 12-24 weeks of pregnancy and is largely independent of maternal age. However, amniocentesis must not be performed in the following cases: (1) Pregnant women with a history of delivery of chromosomally abnormal fetuses and one spouse with a definite chromosomal abnormality. (2) Pregnant women who have received allogeneic blood transfusion, transplantation, cell therapy or immunotherapy within one year will interfere with the results of high-throughput genetic sequencing prenatal screening and diagnosis. (3)Fetus with microdeletion microduplication syndrome or other chromosomal abnormalities are suspected by fetal imaging. (4)People at high risk for various genetic diseases.