Before I introduce the non-invasive DNA prenatal screening technology, I will first tell you why we need to check the fetal chromosomes and what is the need for fetal chromosome testing. Often patients will come to the clinic with the question, why do we need to check the chromosomes of our child? How can we have a child with chromosomal problems when we are a normal couple or have had healthy babies in the past? Is it really necessary to check the chromosomes of our child? Why weren’t these tests done before? In fact, in the most common language, it is like a factory producing defective products, not necessarily a problem with the production line. It’s not necessarily a problem with the production line, but rather the production process has a certain incidence of defective products, not to mention the human body, which is so delicate. Anyone who gets pregnant has the potential to deliver a defective child. The Ministry of Health released the <>, which pointed out that China is a country with a high incidence of birth defects, with about 900,000 new children born with birth defects every year and a birth defect rate of about 5.6%, and the birth defect rate in Hebei Province has also shown a year-on-year increase. From 78.82 cases per million in 2002 to 100.73 cases per million in 2011. Trisomy 21 (Down’s syndrome), the most common chromosomal disorder in humans, has a prevalence of 1/600 to 1/800 in live infants, and the incidence increases with the age of the mother. A significant number of children with Down’s syndrome can be born alive and can survive for a long time. They are mentally retarded, difficult to raise, and can have a variety of complications such as congenital heart disease, which can become a serious burden on family life. Since most pregnant women are under the age of 35, 85% of Downs children born are delivered by pregnant women under the age of 35. This is why prenatal serological screening during pregnancy for pregnant women younger than 35 years of age is especially necessary. Amniocentesis is directly recommended for pregnant women with positive prenatal screening and for women older than 35 years of age at term, where amniotic fluid is extracted and the fetal chromosomes are examined using cells shed from the fetus in the amniotic fluid. The risk of miscarriage associated with amniocentesis is approximately 2 to 5 per 1,000 and the current cost at our hospital is approximately $2,500. The prenatal serological screening we currently use (i.e.: Down’s screening) has a 30 to 40 percent missed diagnosis rate and a 98 percent false positive rate. In other words, even if a high-risk pregnancy is screened for Down’s syndrome, the risk of the child actually having trisomy 21 is about 2 to 3%. That is, out of 100 high-risk pregnant women, about 2 to 3 have a real problem. The above data are obtained without the laboratory data being out of control, but currently not all hospitals can achieve this standard of quality control for prenatal screening, because quality control requires a certain sample size as a basis, but in some primary hospitals, I am afraid there is not that large a sample size. In view of this, the risk value for Down’s syndrome in prenatal screening has been adjusted upward to a value greater than 1/1000, which is recommended for further testing, while the default high risk standard in the current report is 1/270 or 1/350. Even if no problems are found in prenatal screening, there are many ultrasound tests to continue screening for defects, if the ultrasound finds some soft indicators, such as strong fetal ventricular spots, fetal lower abdominal rebound If the ultrasound reveals soft indicators, such as strong light spots in the fetal ventricle, lower abdominal echogenicity, bilateral fetal pelvis separation, widening of the lateral ventricles, and too much or too little amniotic fluid, they are still indications for amniocentesis or cord blood puncture. At this time, the fetus is normal in the vast majority of cases. These soft indicators increase the risk of the fetus by 1 to 2% at most, but doctors are forced to recommend further tests according to the current treatment protocols. As people’s standard of living becomes higher and higher, so does the demand for screening of defective babies. How to improve the detection rate of Down’s syndrome, reduce the false positive rate, and avoid invasive tests to reduce the risk of miscarriage. The non-invasive DNA prenatal screening technique is used to derive the risk rate of fetal aneuploidy by drawing 5 ml of maternal blood directly from the mother at 12 to 24 weeks of gestation, using free fetal DNA from maternal plasma. The technique is currently used to detect trisomy 21 (Down syndrome), trisomy 18 (Edward’s syndrome) and trisomy 13 (Patau’s syndrome). The detection rate is 99.99% and the specificity is ≥99.97% (i.e. false positive rate ≤0.03%). It is currently the closest screening test to prenatal diagnosis. This technique can greatly reduce the psychological burden of pregnant women, without the fear of miscarriage and other injuries caused by puncture stimulation. The results can be obtained two weeks after sampling, which is faster than amniocentesis (amniocentesis usually takes about one month to produce results) and more accurate than prenatal serological screening. The technique is currently expensive, with the test costing $2,480. If the results suggest that the pregnant woman is at high risk, she can undergo further amniocentesis to confirm the diagnosis, as there is still a 3 per 1,000 false-positive probability with non-invasive genetic testing, mainly due to individual differences in the concentration of fetal free DNA in individual pregnant women. If price is not a consideration, the significance of this technology is that it allows 98% of women with high risk of prenatal screening to avoid the risks associated with amniocentesis. In principle, non-invasive DNA prenatal screening can be considered for women who are simply at high risk for Down’s syndrome, with no abnormalities detected by fetal ultrasound, no chromosomal abnormalities in either parent, less than 35 years old, and have not received allogeneic blood transfusion, transplantation, stem cell therapy, or immunotherapy within 1 year. In addition, women who have undergone in vitro fertilization or have other reasons for not being able to conceive easily, women with “precious babies” such as habitual miscarriages, women with twin pregnancies (including identical twins), pregnant women who are too afraid of miscarriage to undergo puncture, pregnant women with contraindications to puncture (e.g., low placenta, signs of miscarriage, hepatitis B, HIV or syphilis infection, RH blood group negative) may be considered. The technique can be considered for pregnant women with contraindications to puncture (such as low placenta, miscarriage, hepatitis B, HIV or syphilis infection, RH blood group negative, severe gestational hypertension, diabetes mellitus, anemia, congenital uterine anomalies, etc.), those who have previously delivered a child with congenital defects and wish to diagnose them early, and those whose fetal ultrasound does not reveal other significant abnormalities. For women older than 35 years, especially those over 37 years, amniocentesis is recommended between 18 and 24 weeks of gestation to detect fetal chromosomes, and this technique is generally not recommended for women older than 37 years because the risk of fetal chromosomal abnormalities is significantly increased in older women older than 37 years, and the incidence of simple Downs children, excluding other chromosomal disorders, is about 1 in 220. The risk of extending this technology to the overall population older than 37 years (given that it throws a 0.03% false positive rate, it is still not a confirmatory criterion) is 1 in 220. If noninvasive genetic testing identifies a fetus as high risk, further amniotic fluid chromosome testing may inconvenience some patients or may increase their time costs. Any good technology is a double-edged sword, how can we use it for the better benefit of our patients? That is why we have to evaluate each patient individually before performing the test, combining ultrasound and age risk, etc. If a patient is older than 37 years old and has no children on her knees, it is possible that this will be her last pregnancy. With the patient’s full informed consent, why not try to save the patient’s time and cost by performing the non-invasive genetic test as soon as possible after 12 weeks of early pregnancy.