Non-invasive prenatal testing (NIPT), sometimes called non-invasive prenatal screening (NIPS), is a method of determining the risk that the fetus will be born with certain genetic abnormalities. The test is particularly sensitive to Down syndrome. This testing analyses small fragments of DNA that are circulating in a pregnant woman’s blood.
What does it test for?
The NIPT is a safe and highly effective way of screening for conditions that include:
- Down syndrome (also called trisomy 21)
- Edwards syndrome (trisomy 18)
- Patau syndrome (trisomy 13)
- Turner syndrome
Some laboratories also test the gender of the baby and look for problems with the sex chromosomes.
The test detects many chromosomal abnormalities, but not as many as a diagnostic test such as amniocentesis. It cannot screen for genetic disorders such as cystic fibrosis, thalassaemia or sickle cell anaemia.
Why have an NIPT?
The NIPT is highly sensitive and picks up more than 99% of cases of Down syndrome. But it is still a screening test rather than a diagnostic test. This means it can only tell you whether there is an increased risk of having a baby with an abnormality, rather than give you a definitive answer.
You might choose to have an NIPT test if:
- Your combined first trimester screening test shows you are at increased risk of having a baby with Down syndrome
- You did not have the combined first trimester screening test because it was too late or the test wasn’t available in your area
- You want to be sure you are at increased risk before you opt for diagnostic tests such as amniocentesis or CVS, which carry a small risk of miscarriage
- You are at increased risk (for example, if you are older or you have had a baby previously with Down syndrome or another chromosomal condition)
What to expect from your NIPT results
It can take up to 2 weeks to get the result of your NIPT. If the result is ‘negative’, ‘normal’ or ‘low risk’, your baby is unlikely to have any of the chromosomal disorders tested. If the result is ‘positive’, ‘abnormal’ or ‘high risk’, this means your baby is likely to be affected.
If you have an abnormal NIPT result, a diagnostic test can confirm the result. You should discuss your options with your doctor or midwife.
