Non-invasive prenatal testing, an alternative option

Non-invasive prenatal testing is a technique used to detect chromosomal and genetic abnormalities in the foetus. It’s particularly recommended to couples with a family history or high risk, although any pregnant woman can have it. It’s performed on a blood sample, so it’s not invasive for the foetus or mother and it’s a highly sensitive test.  It can be performed from the tenth week of pregnancy and the results are ready one to three weeks later, depending on the lab.

This test is similar to amniocentesis or chorionic villus sampling, which are invasive tests because it’s necessary to take samples directly from the woman’s uterus. However, although they have a very high rate of reliability (99%), if the result is positive for some chromosomal or genetic abnormality, it’s recommendable to obtain confirmation by means of more conventional tests.

What is prenatal testing designed for?

The test is designed to detect the most common conditions: Down syndrome, Patau syndrome and Edwards syndrome. But it doesn’t detect all possible abnormalities.

It can’t detect potential foetal malformations, so ultrasound scans are needed for this.

It’s only for single pregnancies, so this screening test is not available for multiple pregnancy.

Is it reliable?

There are different labs that perform this test and they all give similar results in terms of reliability. Recently they have started to include the detection of a greater number of conditions.

In a small percentage of cases it’s necessary to repeat the test due to lack of results. This is because no foetal cells were found in the mother’s blood, which can happen when it’s performed during the early weeks of pregnancy.

Nowadays this test is not covered by the public healthcare system, so it’s expensive, but when used in conjunction with prenatal screening in the first trimester, it’s reliability is almost 100%. If the results are suspicious, your doctor will recommend a more invasive test to confirm them.

These are techniques that are constantly being studied and developed to provide parents with information about the health of their future baby. The tests are becoming ever more reliable and we hope that they’ll be an option for more families.