Can I keep a child with a high-risk baby through non-invasive DNA testing?

Basically every pregnant woman has to undergo a non-invasive DNA test during pregnancy. To be honest, the non-invasive DNA test is a screening method, which is mainly used to screen whether the baby in the mother's belly has Down syndrome. Babies with Down syndrome place a huge burden on both the patients themselves and their families, so non-invasive DNA testing can effectively detect Down syndrome. If the non-invasive DNA result shows high risk, can I keep the child?

Non-invasive DNA testing is mainly used for early screening of fetal aneuploidy of chromosomes 21, 18, and 13. It is mainly suitable for high-grade pregnant women (over 35 years old), people with a history of malformations or stillbirths, or one or both spouses with a genetic disease. Non-invasive high-risk test indicates that the fetus may have chromosomal abnormalities and is at risk of spontaneous abortion, deformity, and stillbirth. It is recommended to do a fetal three-dimensional B-ultrasound at 18-20 weeks of pregnancy, and a chromosome test on amniotic fluid exfoliated cells can also be done. If the results are abnormal, early labor can be induced.

What is non-invasive DNA testing?

Non-invasive genetic testing can be used to detect whether the fetus has an abnormal number of chromosomes. Humans have 23 pairs of chromosomes. If there is one more or one less chromosome, it will cause physical abnormalities. This is an abnormal chromosome number.

However, since this method requires data accumulation, three chromosomal diseases are currently used for clinical testing: trisomy 21, trisomy 18, trisomy 13, etc., that is, there is an extra chromosome 21, chromosome 18 or chromosome 13. Trisomy 21 is the most familiar and common syndrome. Trisomy 18 and trisomy 13 are also accompanied by intellectual developmental disorders, physical deformities and other problems.

Pregnant mothers all know that when they are 15 weeks pregnant, they will be asked to do Down syndrome screening. The purpose of Down syndrome screening is to screen the risk of Down syndrome in the unborn baby in order to avoid the birth of a child with Down syndrome. If the result of Down syndrome screening is high risk, amniocentesis will be needed for further examination. However, amniocentesis has certain risks to the fetus and may cause intrauterine infection or even miscarriage. Some pregnant mothers may need a second puncture, which will increase the risk to the fetus.

Because of this, non-invasive DNA technology is chosen by more pregnant mothers. Pregnant women can choose to go directly for non-invasive DNA testing after 12 weeks. Only 5 ml of venous blood from the pregnant mother is needed, which does no harm to the fetus and the accuracy rate can be as high as over 99%. However, it should be emphasized that non-invasive genetic prenatal testing only detects abnormalities in the number of some chromosomes and cannot replace amniocentesis or B-ultrasound examinations.

Can non-invasive DNA replace amniocentesis?

Although non-invasive genetic prenatal testing has such a high accuracy rate, it cannot be used as the final diagnostic standard. Only amniocentesis can make the final diagnosis. Humans have 23 pairs of chromosomes. Amniocentesis can more comprehensively detect problems with all 23 pairs of chromosomes. It can not only detect abnormalities in the number of chromosomes, but also some major abnormalities in the structure of chromosomes. However, non-invasive genetic prenatal testing currently only detects abnormalities in the number of chromosomes in three of the pairs. Therefore, non-invasive genetic prenatal testing cannot replace amniocentesis, and amniocentesis karyotype analysis remains the gold standard method for fetal chromosome examination.

Therefore, if you just want to rule out trisomy 21 syndrome, then you can only do non-invasive prenatal genetic testing. If you want to know other chromosomes, you will need to do amniocentesis. And let me emphasize again that the accuracy rate is not 100%, so for now we still define this technology as a prenatal screening with a very high accuracy rate, but it is not a definitive diagnosis.