What is Non-invasive Prenatal Testing?


When you’re pregnant, your blood naturally contains small amounts of fragments of your baby’s DNA.

A non-invasive prenatal test (NIPT) is a screen that analyses this DNA in a sample of your blood to predict the chance of Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13) and (if selected) DiGeorge syndrome (22q11.2 deletion). Collecting your blood sample for NIPT poses no threat to your baby.


What does NIPT screen for?

NIPT screens for Down syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13). These conditions are all associated with intellectual disability and congenital malformations; the degree of intellectual disability and the risk and severity of malformations vary with the different disorders.

DiGeorge syndrome (22q11.2 deletion) is also available as an optional screen, if selected. This syndrome can cause heart defects, poor immune system function, a cleft palate and low levels of calcium in the blood. Its features vary widely, even among people with the same chromosome deletion.

Sex chromosome abnormalities, such as Turner syndrome (45,X) and Klinefelter syndrome (47,XXY), can also be detected, but with reduced accuracy. Sex chromosome abnormalities are often clinically milder than other chromosomal abnormalities. Testing for sex chromosome abnormalities will also reveal the fetal sex.

What is different about NIPT?

In recent decades, screening for chromosome abnormalities during pregnancy has been called ‘first trimester screening’ (FTS). FTS and NIPT are very different types of tests, both in what they test and the accuracy of their results. However, together they offer you very important information about your developing baby.

First trimester screening combines the results of biochemical blood tests with the structural findings measured under ultrasound to predict the chance that your baby has a chromosomal or other structural abnormality.

NIPT is a genetic test that analyses your baby’s DNA fragments that are circulating in your bloodstream to detect the most common chromosomal abnormalities. By directly analysing your baby’s DNA, NIPT results have been shown to be more accurate and have fewer false positives (i.e. abnormal results that are incorrect) and fewer false negatives (i.e. normal results that are incorrect) than FTS in identifying Down syndrome cases.

How accurate is NIPT?

NIPT is more accurate than traditional first trimester screening and much less likely to give a false positive or false negative result. That means there will be much less chance your doctor would recommend follow-up testing, such as amniocentesis.

Why the Harmony Prenatal Test?

Since NIPT first became available in early 2013, there have been changes to test methodologies and new evidence has emerged about test performance. We carefully reviewed the evidence regarding the accuracy and reliability of different forms of NIPT, and chose the Harmony Prenatal Test. We constantly review the medical literature on NIPT to ensure that we are providing you with a test that meets these high standards.

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