Pregnancy brings a lot to think about, and for many parents, understanding their baby’s chance of a chromosomal condition is part of that. A non-invasive prenatal test, or NIPT, is one of the most accurate ways to get that information early.
It combines a short scan with a simple blood test, and is safe for both you and your baby. Here is what it involves, what it can tell you, and what your results mean.
of pregnancies with trisomy 21 (Down’s syndrome) are detected
false-positive rate
View as table
| Statistic | Value |
|---|---|
| of pregnancies with trisomy 21 (Down’s syndrome) are detected | 99% |
| false-positive rate | 0.1% |
01What a NIPT is
NIPT is a screening test that involves an ultrasound and a blood test. It examines small fragments of DNA called cell-free DNA (cfDNA), shed from the placenta into your bloodstream, to assess the chance of Down’s, Edwards’ or Patau’s syndromes.
It can detect several chromosomal conditions from as early as 10 weeks, and is highly accurate. It can also assess sex chromosome anomalies, including Turner and Klinefelter syndromes. The test is suitable for single and twin pregnancies (though in non-identical twins it cannot give a twin-specific chance), and works well for IVF and surrogate pregnancies too.
It is important to remember that NIPT is a screening test, not a diagnostic one. If it shows an increased chance of a condition, further testing is needed to confirm.
NIPT gives you information early and gently. No needles for your baby, just a blood sample from you.
The pregnancy scanning team
02When can I have a NIPT test?
You can have NIPT from 10 weeks of pregnancy, earlier than other, more invasive diagnostic tests, giving you more time to consider and respond to your results. It remains available later in pregnancy too, useful if you missed the earlier window or had a previous pregnancy affected by a genetic condition.
NIPT is entirely your choice and never mandatory. Talk it through with your specialist alongside any other screening you are considering, so you choose what is right for your pregnancy.
03What to expect from the process
- 1
Preparing for your test
Drink a few glasses of water in the hour before your ultrasound, to help improve visibility.
- 2
Ultrasound scan
A brief, non-invasive scan confirms you are at the 10-week-plus gestational mark needed for testing.
- 3
Blood sample
A blood sample is taken from your arm and sent to a specialist laboratory for analysis.
- 4
Your results
Your results are typically ready within three to five working days, with a report outlining your baby’s chance of the conditions tested.
- 5
Afterwards
No special care or downtime is needed. You can resume your normal activities straight away, following any specific advice from your doctor.
04What NIPT can detect
As a screening tool, NIPT can flag a number of things about your developing baby.
- Chance of trisomy 21, 18 or 13, indicating whether your baby has a higher or lower probability of Down’s, Edwards’ or Patau’s syndrome. A result below 1 in 10,000 is considered very low chance.
- Your baby’s sex, useful if you want to know early, or want to plan ahead.
- Sex chromosome aneuploidy, differences in the number of X and Y chromosomes, which can occasionally cause learning, behavioural or other health considerations.
- Monosomy X (Turner syndrome), a condition affecting females missing an X chromosome, which can involve heart, learning or endocrine differences.
NIPT is highly accurate: it identifies around 99% of pregnancies affected by trisomy 21, with a low false-positive rate of around 0.1%.
05Understanding your results
Results come back as one of three outcomes: low chance, increased chance, or inconclusive.
A low chance result means it is very unlikely your baby is affected by the conditions tested. An increased chance result means the possibility is higher, and, because the DNA sampled comes from the placenta rather than the baby directly, a confirmatory test such as CVS or amniocentesis is always recommended before any diagnosis is made.
Occasionally: in around 5% of cases: a result is inconclusive, usually because there was not enough of your baby’s DNA in the sample. If this happens, we will usually take a second sample; if the test cannot produce a result twice, it will be reported as failed. If you receive an inconclusive result, our specialist will contact you and talk through what happens next.
Your doctor or midwife may want a copy of your results, and if you have any questions, our on-site consultant obstetricians are available to talk them through with you.
06What happens next
For a detailed structural assessment of your baby, many parents follow NIPT with an anomaly scan between 18 and 24 weeks. Whatever your results show, our team is here to explain them clearly and support you through the next step.
