NIPT is a highly accurate blood test offered on the NHS after a higher chance combined or quadruple screening result. It analyses fragments of your baby's DNA in your blood to screen for Down's syndrome, Edwards' syndrome, and Patau's syndrome, with a detection rate above 99% for Down's. It is a screening test, not a diagnosis, so a higher chance result will be followed up with diagnostic testing.
During pregnancy, the placenta releases tiny fragments of DNA into your blood. These fragments are called cell-free DNA (cfDNA). Although they come from the placenta rather than directly from the baby, the placental DNA is almost always genetically identical to the baby's.
NIPT works by taking a simple blood sample from your arm and analysing these cfDNA fragments using advanced sequencing technology. The laboratory looks at whether there is more DNA than expected from chromosomes 21, 18, or 13. An excess of chromosome 21 material, for example, may indicate Down's syndrome.
Because NIPT reads DNA directly rather than relying on indirect markers like blood hormone levels, it is significantly more accurate than the combined test.
On the NHS, NIPT is offered as a second-stage screening test. You cannot request it as a first-line test through the NHS pathway. It is available when your combined test result shows a higher chance (between 1 in 2 and 1 in 150) for Down's syndrome, or a joint higher chance for Edwards' and Patau's syndromes, or when your quadruple test result shows a higher chance for Down's syndrome.
NIPT can be performed from around 10 weeks of pregnancy, though in the NHS pathway you will typically be offered it after receiving your combined test results, so usually from around 12 to 14 weeks.
The test is also available for twin pregnancies and IVF pregnancies, including those using donor eggs.
NIPT is not currently available on the NHS for pregnancies with three or more babies, or for anyone who has cancer (unless in remission), as the presence of tumour DNA in the blood can interfere with results.
NIPT screens for three specific conditions: Down's syndrome (trisomy 21), Edwards' syndrome (trisomy 18), and Patau's syndrome (trisomy 13). Its detection rate for Down's syndrome is above 99%, making it substantially more accurate than the combined test's roughly 85% detection rate.
However, NIPT is still a screening test, not a diagnostic one. It tells you whether your baby has a higher or lower chance of having one of these conditions. It cannot give you a definitive yes or no. A small number of results will be false positives (the test says higher chance, but the baby does not have the condition) or, more rarely, false negatives.
False results can occur because of something called confined placental mosaicism, where the placenta has different genetic material from the baby. This is uncommon but is the main reason NIPT cannot replace diagnostic testing entirely.
NIPT does not screen for structural abnormalities, single-gene disorders, or other chromosomal conditions beyond the three trisomies. Your 20-week anomaly scan is a separate check for physical development.
Within the NHS screening programme, NIPT will not be used to determine the sex of your baby.
Results typically take 7 to 14 working days, depending on your local laboratory.
Lower chance result. This means NIPT found no increased level of chromosomes 21, 18, or 13. The chance of your baby having one of these conditions is very low. No further screening is needed, though you will still be offered your routine anomaly scan at 20 weeks.
Higher chance result. This means NIPT detected an increased level of one of the three chromosomes. A higher chance NIPT result is more significant than a higher chance combined test result because NIPT is much more accurate. However, it is still not a diagnosis. You will be offered a diagnostic test (CVS or amniocentesis) to confirm whether the condition is present.
No result / failed test. In a small percentage of cases, NIPT does not give a result. This is usually because there was not enough fetal DNA in the blood sample. This can happen if the test was done very early in pregnancy, or occasionally with a higher BMI. A repeat blood draw may be offered, or your healthcare team may discuss other options with you.
When you receive a higher chance result from your combined or quadruple test, you have three choices. You can choose NIPT, which is a blood test with no risk to the baby. You can choose a diagnostic test (CVS or amniocentesis), which gives a definitive answer but carries a small risk of complications. Or you can choose not to have any further testing and continue your pregnancy without additional screening.
There is no pressure to choose any particular path. Your screening midwife or coordinator will talk you through each option so you can make the decision that feels right for you.
If you would prefer to have NIPT without going through the NHS screening pathway first, several private providers offer it from around 10 weeks of pregnancy. Common private NIPT brands in the UK include Harmony, Panorama, and SAFE test. Private NIPT typically costs between 350 and 500 pounds and may screen for additional conditions beyond the three trisomies, such as sex chromosome conditions (Turner syndrome, Klinefelter syndrome) and some microdeletion syndromes.
Private NIPT may also reveal the sex of your baby if you choose that option.
It is worth noting that private NIPT uses the same underlying technology as NHS NIPT. The key difference is access: NHS NIPT is only offered after a higher chance screening result, while private NIPT is available to anyone willing to pay.
If a private NIPT result comes back as higher chance, you should be referred into the NHS pathway for diagnostic testing and support.
Waiting for any screening result can be stressful, and navigating decisions about further testing can feel overwhelming. You do not have to make decisions immediately.
Antenatal Results and Choices (ARC) provides impartial, non-directive support through a confidential helpline (0207 713 7486) staffed by trained professionals who understand the screening pathway.
Your screening midwife or coordinator is available to explain results, answer questions, and support you through next steps.
Tommy's offers free, evidence-based pregnancy information and a midwife helpline for any pregnancy-related concern.
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