After a positive HCG, the family rejoiced, but the rejoicing did not last long, followed by months of early pregnancy vomiting. The next thing you need to do is to decide which hospital you want to go to for the delivery, and whether to go to a specialist or a general practitioner. But the most difficult thing for pregnant mothers is to choose between Down’s syndrome, non-invasive and amniocentesis. First of all, the advantages and disadvantages of the various tests Down’s syndrome screening advantages and disadvantages ① advantages: affordable (two to three hundred dollars), non-invasive (only need to take venous blood) ② disadvantages: low detection rate and accuracy (even the most comprehensive early and mid-term combined screening can only detect 80-90% of the affected children), high rate of false positives (a large proportion of high-risk Down’s syndrome screening is not confirmed by the final diagnosis). Advantages and disadvantages of non-invasive NDA ①Advantages: non-invasive (only venous blood is needed), high detection rate (99% of children can be detected), low false-positive rate (very few children with high risk of non-invasive screening are not diagnosed). ②Disadvantages: high cost (more than 2,000 – 3,000 across the country), narrow detection area (currently high accuracy for trisomy 21, 18, 13, slightly lower accuracy for sex chromosomes, limited accuracy for other chromosomes (other chromosomal abnormalities often also show up as high risk for Down screening). However, non-invasive testing has covered common chromosomal aneuploidy disorders). Advantages and disadvantages of amniocentesis ①Advantages: 46 chromosomes can be detected at once, not only for numerical abnormalities but also for structural abnormalities >10M. In addition, gene chip and single gene disease detection can be performed. High accuracy (the gold standard for chromosomal disease diagnosis) is one of the most extensive and accurate prenatal diagnostic techniques available. ②Disadvantages: There are certain risks (miscarriage rate 0.5-1‰), and in rare cases, cell culture will fail and other tests or re-puncture will have to be done. How exactly should I choose? 1. Affordable combination: Down’s screening → non-invasive DNA → amniocentesis Down’s screening first: high risk or other risk factors before non-invasive or amniocentesis, this combination is low cost and safe, and the number of mothers having amniocentesis will be reduced significantly because of the addition of non-invasive. However, this combination will miss about 10% of children with Down’s syndrome. It is suitable for ordinary pregnant mothers with no high risk factors, who are frugal. 2.Luxury combination Non-invasive DNA → Amniocentesis Non-invasive DNA is done directly without Down’s syndrome screening, and then amniocentesis is done for non-invasive high risk or with other risk factors, because of the direct application of non-invasive, this combination has high cost and high detection rate, which can detect 99% of children with Down’s syndrome. The drawback of this combination is that it misses a very small number of children with structural chromosomal abnormalities. It is suitable for ordinary pregnant mothers with no high-risk factors, and is a luxury type. 3.Precise combination High risk factor → amniocentesis This combination has the highest detection rate and can detect all chromosome number abnormalities, such as SNP gene chip can detect chromosome microdeletion, microduplication, heterozygous deletion and uniparental diploidy. It is particularly suitable for pregnant mothers with a history of abnormal births, family history and other high-risk factors.