NIPT: what it screens for and what the results mean
NIPT (noninvasive prenatal testing), also called cell-free DNA screening, is a blood test that looks at DNA from the placenta in your blood. It’s a screening test, so it gives a chance rather than a definite answer.
US and UK differences
| US (ACOG) | UK (NHS screening programme) | |
|---|---|---|
| When | From 10 weeks | Up to 21 weeks and 6 days |
| Who | A screening option to discuss with your ob-gyn | After a higher-chance result (1 in 2 to 1 in 150) from the combined or quadruple test |
| Looks for | Down syndrome, Patau syndrome, Edwards syndrome and problems with the number of sex chromosomes | Down’s, Edwards’ and Patau’s syndromes only |
| Baby’s sex | Ask the provider what’s reported | Not assessed |
| Results | In about 1 week | Ask your screening team |
The UK offer covers single and twin pregnancies, including IVF and donor egg pregnancies, but not triplets or more. Samples may be kept for up to 5 years.
What the results mean
A lower-chance or negative result doesn’t rule out a condition. A higher-chance or positive result doesn’t mean your baby definitely has one, and the NHS says most people with a higher-chance screening result have babies without these conditions.
ACOG says a positive result should be followed by a diagnostic test, CVS or amniocentesis. In the UK, after a higher-chance screening result, your choices are no further test, NIPT, or CVS or amniocentesis. Talk through your result with your doctor or midwife before deciding.
How accurate is it? False positives and negatives
False positives and false negatives can happen. ACOG suggests asking for the rates for the test you’re having. The UK programme says NIPT is less accurate after a very high-chance result for Edwards’ or Patau’s syndrome, meaning between 1 in 2 and 1 in 10.
We haven’t listed an accuracy percentage here, because the official pages we read don’t give one.
Can NIPT tell you the baby’s sex or gender?
The NHS version doesn’t. Some other tests report sex chromosomes, so ask the provider what’s included. Compare every way to find out the sex.
Questions people ask
Is NIPT a diagnosis?
No. It’s a screening test. ACOG says a positive result should be followed by CVS or amniocentesis.
How early can you have NIPT?
ACOG says it can be done from 10 weeks. On the NHS it’s offered after a higher-chance combined or quadruple test, up to 21 weeks and 6 days.
Can NIPT tell you the gender?
The NHS version doesn’t assess it. Some other tests report sex chromosomes, so ask the provider what’s included.
How is NIPT done?
It’s a blood sample from you. The test looks at DNA from the placenta in your blood.
References
- UK Government: Fetal anomaly screening programme handbook, NIPT and screening for Down’s, Edwards’ and Patau’s syndromes
- NHS: Screening for Down’s, Edwards’ and Patau’s syndromes
- ACOG: Prenatal genetic screening tests
Advice differs between countries, so follow your own care team’s plan. How we check this.
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