Frequently asked questions
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.
NIPT screens for Down syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13). They cause moderate to profound intellectual disability and are associated with major congenital malformations.
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 gender.
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 result that are incorrect) and fewer false negatives (i.e. normal results that are incorrect) than FTS in identifying Down syndrome cases.
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.
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.
Your results are sent to your doctor in 5–8 business days from the day your blood sample was collected.
In rare cases (less than 3%), the laboratory is unable to obtain a result from the first sample. This can occur in samples where there is not enough of the baby’s DNA. Further testing may be required (at no additional cost), and could therefore delay the result. If no result is obtained from the second sample, you may be offered a re-test free-of-charge. In patients where a re-test is requested, approximately two-thirds produce a result on the second sample. If no result is possible, a full refund may be offered.