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 disturbed quality parameters, or because there is too little DNA of the baby in the mother's blood (low fetal fraction). This does not necessarily mean that there is an increased risk of trisomy 21, 18 or 13. 

Second NIPT analysis (free of charge if the previous NIPT was also performed at UZ Leuven): in most cases, a second NIPT test on a new blood sample 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.

Third NIPT analysis (free of charge if the previous NIPT analyses were also performed at UZ Leuven): if the second NIPT is still not interpretable (extremely rare), your doctor or a clinical geneticist from our center will inform you and offer you the necessary multidisciplinary care. In specific cases (after 20 weeks and on condition of normal ultrasound findings at the 20-week ultrasound), a third NIPT analysis can be performed. In other cases, an invasive test (amniocentesis) may be indicated to detect rare chromosomal abnormalities in your baby. 

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, unless in exceptional cases a second or third blood sample is requested on our advice.

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 mother is obese.
• The mother has (had) cancer.
• The mother has lupus or another autoimmune disease.
• 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. 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) in line with the general policy at UZ Leuven.

See current clinical trials.

• Parijs, I. et al. Population screening for 15q11-q13 duplications: corroboration of the difference in impact between maternally and paternally inherited alleles. Eur J Hum Genet 32(1): 31-36 (2024)
• Lannoo, L. et al. Rare Autosomal Trisomies and Adverse Perinatal Outcomes. N Engl J Med. 391(2):184-185 (2024)
• Lannoo, L. et al. What helps define outcomes in persistent uninterpretable non-invasive prenatal testing: Maternal factors, fetal fraction or quality scores? Pren Diagn 43(10): 1333-1343 (2023)
• Lenaerts, L. et al. Non-invasive prenatal testing: when results suggests maternal cancer. Med Genet 35(4): 285-295 (2023)
• Lannoo, L. et al. A cross-country comparison of pregnant women's decision-making and perspectives when opting for non-invasive prenatal testing in the Netherlands and Belgium. Prenat Diagn 43(3):294-303 (2023)
• 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. Outcome of publicly funded nationwide first-tier noninvasive prenatal screening. Genet Med 23:1137-1142 (2021)
• van Riel, M. et al. Performance and Diagnostic Value of Genome-Wide Noninvasive Prenatal Testing in Multiple Gestations. Obstet Gynecol 137(6):1102-1108 (2021)
• Lenaerts, L. et al. Pregnant women with confirmed neoplasms should not have noninvasive prenatal testing. Prenat Diagn 39(12):1162-1165 (2021)
• Lenaerts, L. et al. Breast Cancer Detection and Treatment Monitoring Using a Noninvasive Prenatal Testing Platform: Utility in Pregnant and Nonpregnant Populations. Clin Chem 66(11):1414-1423 (2021)
• Lenaerts, L. et al. Comprehensive genome-wide analysis of routine non-invasive test data allows cancer prediction: A single-center retrospective analysis of over 85,000 pregnancies. EClinicalMedicine 35:100856 (2021)
• Lannoo, L. et al. Non-invasive prenatal testing suggesting a maternal malignancy: What do we tell the prospective parents in Belgium? Prenat Diagn 41(10):1264-1272 (2021)
• Lenaerts, L. et al. Noninvasive Prenatal Testing and Detection of Occult Maternal Malignancies. Clin Chemistry  65(12):1484-1486 (2019)
• Brison, N. et al. Maternal copy-number variations in the DMD gene as secondary findings in noninvasive prenatal screening. Genet Med 21:2774-2780 (2019)
• 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).