Non-invasive prenatal testing (NIPT)

Most of the pregnancies go to term uneventfully, but sometimes specific changes are detected in the fetal development that may indicate abnormality in the fetal genetic material. Some of these abnormalities are numerical chromosomal changes, where the fetus has an extra chromosome compared to normal chromosomal number.

For example, in the most common chromosomal abnormality syndrome, Down syndrome, the fetus has three copies (trisomy) of chromosome 21 instead of the normal two. Other common chromosome abnormality syndromes are trisomy 18, where the fetus has three copies of chromosome 18, and trisomy 13, where the fetus has three copies of chromosome 13.

NIPT is a non-invasive screening test that can be used to predict the risk of chromosomal changes in the fetus. NIPT cannot be used as a diagnostic test.

Participation in fetal screening tests is always voluntary. You can get information about fetal screening tests from your own Child Welfare Clinic/Family Center (neuvola). At the Child Welfare Clinic/Family Center (neuvola), a referral will be made for an early pregnancy ultrasound scan, after which you will be referred for NIPT if you wish.

NIPT analyses the cell free fetal DNA (cffDNA). This is released by the placenta and it can be reliably detected in maternal blood from pregnancy week 10 onwards. One sample of venous blood is drawn from the mother for the test, and it is sent for analysis to the Genomics laboratory of Turku University Hospital.

Sometimes the results may be delayed due to technical reasons, or sometimes a new sample is needed because the amount of cffDNA is too low for the analysis in the original sample. The test results are always interpreted by health care professionals.

As the name of the test indicates, NIPT is a non-invasive test, which means that the screening of the fetal genetic abnormalities can be performed from a maternal blood sample. By using a non-invasive test, the small risk of miscarriage carried by invasive procedures is avoided. The NIPT can be performed from the pregnancy week 10 onwards. NIPT can also be performed in twin pregnancies and in pregnancies resulting from donor eggs or embryos.

NIPT is not a diagnostic test. NIPT is a screening test, that provides a computational risk of chromosomal abnormality for the fetus. Screening test means that there is always a small risk for false positive and false negative result. As a result, it is extremely important to confirm abnormal NIPT results with invasive amniotic fluid testing. Normal result does not exclude the possibility that the fetus has a genetic abnormality that the NIPT test is not designed to detect. Other factors that may affect the results of the test are maternal obesity, certain medications and organ transplantations. If the pregnancy has started as a twin pregnancy but the other twin is lost early on, NIPT is not recommended.

If a chromosomal abnormality is detected in twin pregnancy, it is not possible to conclude which fetus is affected, and therefore the results should be confirmed with amniotic fluid testing.

How is NIPT done

Benefits of the test

Limitations of the test