Non-invasive prenatal test (NIPT)

In rare cases, the NIPT cannot reliably estimate the risk of either trisomy 21, 18 or 13 in the baby. This does not necessarily mean that there is an increased risk of trisomy 21, 18 or 13. In most cases, the presence of a trisomy 21, 18 or 13 can be excluded by repeating the NIPT on a second blood sample (free of charge). You can visit your physician should you wish to have the NIPT repeated or to discuss whether further ultrasound follow-up is appropriate.

Exceptionally, the NIPT fails to provide a reliable result. This can be caused, for example, by a technical reason or because there is too little DNA from the baby in the mother's blood. This does not necessarily mean that there is an increased risk of trisomy 21, 18 or 13. In most cases, a second NIPT test on a new blood sample (free of charge) does provide a reliable result. You can visit your physician to have a new blood sample taken or to discuss whether further ultrasound follow-up is appropriate.

If too little DNA from the baby was present in the first blood sample, we recommend that the new blood sample is only taken from 14 days after the first blood sample. In this way, the chance of a reliable test result is much higher.

Because NIPT analyses all chromosomes, in rare cases it can also detect other chromosomal abnormalities (see above). Should this be the case, your physician or one of our centers’ clinical geneticists  will inform you accordingly and offer you the necessary multidisciplinary care.

• Only a blood sample from the mother is required.
• No increased risk for a miscarriage.
• No risk for the mother or her baby.

• From the 12th week of gestation onwards.
• Only if, during this pregnancy, NIPT has not already been performed and reimbursed by the public health insurance.

Since November 2013, over 100,000 analyses have been completed successfully in our center.

• NIPT has an unprecedented sensitivity for detection of trisomy 21, 18 and 13 in the baby.
• An overview of the diagnostic experience and reliability of NIPT at UZ Leuven can be found in this brochure.
• In some cases, the NIPT result is false positive.
  • In this case the test results indicate that the baby has a trisomy, whereas this is not true.
  • An abnormal test result should therefore always be confirmed by an invasive test (preferably by amniocentesis).
• In some cases, the NIPT result is false negative.
  • With a normal NIPT result, there is still a small chance that your baby may still have a chromosomal abnormality.

A number of factors can affect the reliability of NIPT. It is important to communicate these so that we can take them into account when interpreting the results:

• Monozygotic or dizygotic twin pregnancy or multiple pregnancy (identical and non-identical twins).
• Pregnancy with a ‘vanishing twin’ (original twin pregnancy with one baby deceased early in pregnancy).
• The weight of the mother prior to the pregnancy exceeded 100 kg.
• The mother has (had) cancer.
• The mother has lupus.
• The mother is on heparin therapy.

NIPT is not appropriate in case of:

• Ultrasound abnormalities in your baby (including a nuchal translucency thickness exceeding 3.5mm).
• The mother has had one of the following treatments:
  • Stem cell therapy
  • Organ transplant

The center of human genetics of UZ Leuven is committed to continuously improve the quality of our care and testing. With the permission of the ethics committee, the residual material and genomic data obtained after NIPT can be used for validation, internal quality control or research purposes (for example, optimization of the NIPT and new developments).

See current clinical trials.

• Lannoo, L. et al. Rare autosomal trisomies detected by non-invasive prenatal testing: an overview of current knowledge. Eur J Hum Genet 30(12):1323-1330 (2022)
• Van Den Bogaert, K. et al. (2021) Outcome of publicly funded nationwide first-tier noninvasive prenatal screening. Genet Med
• Lenaerts, L. et al. (2019) Noninvasive Prenatal Testing and Detection of Occult Maternal Malignancies. Clinical Chemistry
• Brison, N. et al. (2019) Maternal copy-number variations in the DMD gene as secondary findings in noninvasive prenatal screening. Genet Med
• Villela, D. et al. Fetal sex determination in twin pregnancies using non-invasive prenatal testing. NPJ Genom Med 4:15 (2019)
• Brison, N. et al. Predicting fetoplacental chromosomal mosaicism during non-invasive prenatal testing. Prenat Diagn 8(4):258-266 (2018)
• Neofytou, M. et al. Maternal liver transplant: Another cause of discordant fetal sex determination using cell-free DNA. Prenat Diagn 38(2):148-150 (2018)
• Brison, N. et. al. Accuracy and clinical value of maternal incidental findings during noninvasive prenatal testing for fetal aneuploidies. Genet Med 19(3):306-313 (2017)
• Brady, P. et al. Clinical implementation of NIPT – technical and biological challenges. Clin Genet 89(5): 523-30 (2016)
• Amant, F. et al. Presymptomatic identification of cancers in pregnant women during noninvasive prenatal testing. JAMA Oncology 1(6): 814-9 (2015)
• Vandenberghe, P. Non-invasive detection of genomic imbalances in Hodgkin/Reed-Sternberg cells in early and advanced stage Hodgkin's lymphoma by sequencing of circulating cell-free DNA: a technical proof-of-principle study. Lancet Haematol 2(2):e55-65 (2015)
• Bayindir, B. et al. Noninvasive prenatal testing using a novel analysis pipeline to screen for all autosomal fetal aneuploidies improves pregnancy management. Eur J Hum Genet 23(10): 1286-93 (2015).