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What are prenatal DNA tests?

The prenatal DNA test, also known as a non-invasive prenatal test, is a genetic test that is performed on pregnant women from the 10th week of pregnancy, in order to detect early if the fetus has any type of chromosomal abnormality.

This test has a high percentage of effectiveness and with it, you can detect alterations such as those that cause Down Syndrome or Di George syndrome, which are genetic disorders caused by trisomies in certain pairs of chromosomes or by losses of genetic material.

This is an advanced, risk-free, and completely reliable scientific method that replaces invasive tests.

Types of prenatal DNA tests that exist

Basic non-invasive prenatal test

With this test, the most frequent chromosomal abnormalities are detected, such as Down Syndrome, Edwards Syndrome, and Pataú Syndrome, which are trisomy 21, trisomy 18, and trisomy 13 respectively.

Another result that can be known after this analysis is the sex of the baby.

Extended non-invasive prenatal test

Obviously, this is a more complete analysis that in addition to detecting the same thing that the basic prenatal DNA test reveals, is also capable of detecting losses in the chromosomal material of the fetus that can affect their normal development and give rise to genetic disorders such as Prader-Willi Syndrome, Di George Syndrome, among others.

How is the prenatal DNA test performed?

The test involves the analysis of a blood sample that is taken from the mother., because DNA from the fetus circulates in the bloodstream of this. Being a non-invasive test, it is completely safe and avoids endangering both the mother and the embryo, since the risks of injuries and abortions that are reported after invasive examinations are significantly reduced.

When and why should a pregnant woman have a non-invasive prenatal test?

The non-invasive prenatal test is advised from week 10 of pregnancy in women with weight considered normal and from week 14 in pregnant women with obesity.

Although the obstetrician-gynecologist can indicate this test to healthy patients with no history who wish to know if their baby is at risk of presenting any genetic abnormality, the non-invasive prenatal DNA test has been created to be applied especially in the following cases:

  • Elderly pregnant women
  • Very young pregnant women (under 17 years old)
  • Family history with a history of trisomies
  • High risk of Down syndrome
  • Predisposition to fetal genetic abnormalities

Results of the non-invasive prenatal test

Generally, the results of this test are delivered between 10 and 15 business days after the sample has been taken. If they come out positive, they indicate that the fetus has a higher risk of suffering from a chromosomal disorder.

For the detection of Trisomy 21, the prenatal DNA test has a rate of 99.44%, while for the detection of trisomy 13 and trisomy 18 the detection rate is 95%, that is, it is considered a reliable test, however, some specialists indicate to the mother to perform other tests and tests such as amniocentesis, to confirm the diagnosis, in case of any positive result.

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