How NIPT (new prenatal diagnosis) works

How NIPT (new prenatal diagnosis) works

This article is about how NIPT works.
More technical information about NIPT (new prenatal diagnosis), including how the test works and what to look out for.

A more specialized testing mechanism for NIPT (new prenatal diagnosis)

What is the NIPT (new prenatal diagnosis) test?

Pregnant women's blood contains DNA fragments derived from their babies; NIPT can detect possible Down syndrome (21 trisomies) and Edwards syndrome (18 trisomies) and Pato syndrome (13 trisomies) by analyzing the DNA fragments derived from the babies. Therefore, it is important to note that the NIPT test cannot be performed on triplets or more because the DNA fragments cannot be identified.

Mechanism of negative/positive judgment

In NIPT (new prenatal diagnosis), information is first read from each individual DNA fragment. Next, the DNA fragments are classified according to the chromosome number from which they originate. After classification, the quantitative ratio of DNA fragments derived from chromosomes 21, 18, and 13 is used to detect changes in specific chromosomes, which are then compared to standard values to determine whether the test is negative or positive.

In the case of Down's Syndrome

For example, if a baby has Down syndrome, chromosome 21 is involved. Normally, there are two chromosomes 21, but if the baby has Down syndrome, there are three. This means that the baby will contain 1.5 times the normal number of chromosome 21, and the test result will be positive.