NIPT Blood Test: Complete Guide
NIPT (Non-Invasive Prenatal Testing) is a blood test that screens for chromosomal conditions and can also determine your baby's sex. Here is everything you need to know about how it works, when you can have it, and whether it is right for you.
Table of Contents
- What Is NIPT?
- When Can You Get NIPT?
- How Accurate Is NIPT?
- NIPT on the NHS
- NIPT Cost UK
- NIPT vs Nub Theory
- Frequently Asked Questions
What Is NIPT?
NIPT analyses fragments of fetal DNA that circulate in your bloodstream during pregnancy — known as cell-free fetal DNA (cffDNA). From as early as ten weeks, enough fetal DNA is present in a maternal blood sample for the test to work. NIPT screens for chromosomal conditions including:- Down syndrome (Trisomy 21) — the most commonly tested condition
- Edwards syndrome (Trisomy 18) — a serious chromosomal condition
- Patau syndrome (Trisomy 13) — another serious chromosomal condition
Some NIPT packages also screen for sex chromosome conditions (such as Turner syndrome or Klinefelter syndrome) and certain microdeletions, depending on the provider and the package chosen.
NIPT can also determine fetal sex with a high degree of accuracy. Because the test analyses fetal DNA directly, it can detect the presence of a Y chromosome, indicating a male pregnancy, or its absence, indicating a female pregnancy.
It is important to understand that NIPT is a screening test, not a diagnostic test. A high-risk result does not confirm that your baby has a chromosomal condition — it means further testing, typically amniocentesis or chorionic villus sampling (CVS), would be needed to diagnose with certainty.
When Can You Get NIPT?
NIPT can be performed from ten weeks of pregnancy. A simple blood sample is taken from your arm, no ultrasound is required for the test itself, and there is no risk to the baby from the procedure. The sample is sent to a laboratory where the fetal DNA is analysed.If you are having NIPT through the NHS as part of the combined screening pathway, it will be offered alongside or after your 11–14 week scan. If you are going privately, you can usually book from ten weeks onward.
How Accurate Is NIPT?
NIPT has a high detection rate for the three main chromosomal conditions it screens for. For Down syndrome (Trisomy 21), the detection rate is generally reported as over 99%, with a very low false-positive rate. Detection rates for Edwards syndrome (Trisomy 18) and Patau syndrome (Trisomy 13) are somewhat lower but still high compared to earlier screening methods such as the combined test.For sex determination, NIPT is highly accurate from ten weeks onward. Results are more reliable as pregnancy progresses and fetal DNA levels in the maternal bloodstream increase.
Occasionally NIPT returns a "no result" or "inconclusive" outcome, which usually means insufficient fetal DNA was detected in the sample. This is more likely in very early pregnancies or in women with a higher BMI. In these cases the test may be repeated.
NIPT is not 100% accurate and does carry a small false-positive rate. A positive or high-risk result should always be discussed with a midwife, genetic counsellor, or doctor before any further decisions are made.
NIPT on the NHS
The NHS offers NIPT — known as the SAFE test within the NHS pathway — to pregnant women who are identified as higher risk following the combined screening test at 11 to 14 weeks. The combined test uses nuchal translucency measurement from an ultrasound, together with blood markers, to calculate a risk level. If your combined test result places you in the higher-chance category, you will be offered NIPT free of charge as the next step.If your combined screening result places you in the lower-chance category, NHS NIPT is not routinely offered. You can still choose to have NIPT privately if you would like additional reassurance or wish to find out your baby's sex.
NIPT Cost UK
Private NIPT in the UK typically costs between £150 and £500, depending on the provider and the package you choose. The price variation reflects differences in what is screened for: some packages cover only the three main trisomies, while others include sex chromosome conditions, microdeletions, and sex determination.Well-known private NIPT providers in the UK include Harmony, Panorama, and the SAFE test offered through various private hospitals and clinics. When comparing providers, consider what conditions are included in the screen, turnaround time for results, and whether a genetic counsellor is available to discuss your results.
NIPT vs Nub Theory
NIPT and nub theory serve quite different purposes, though both can tell you your baby's sex.| Feature | NIPT | Nub Theory |
|---|---|---|
| Available from | 10 weeks | 12–13 weeks (scan needed) |
| Sex accuracy | Very high | Good at 13+ weeks |
| Screens for chromosomal conditions | Yes | No |
| Cost | £150–£500 privately; free if NHS-referred | Free (uses existing scan images) |
| Requires a blood test | Yes | No |
NIPT is far more accurate than nub theory for sex determination, and it additionally screens for chromosomal conditions that nub theory cannot detect at all. However, for parents whose sole goal is to find out the sex early and who are not seeking chromosomal screening, nub theory is a free, non-invasive option that can be explored using their existing scan images. Many parents use both: nub theory for an early, fun indication, and NIPT or an anatomy scan for a definitive answer.
Frequently Asked Questions
### Is NIPT worth it if I just want to know the gender?If your only goal is early sex determination, nub theory at 12 weeks or later is free and does not require an additional test. NIPT is significantly more expensive for that purpose alone. However, NIPT also screens for serious chromosomal conditions — many parents find that information valuable regardless of whether sex determination was their original motivation. The decision is personal and depends on what reassurance means to you.
How long do NIPT results take?
Private NIPT results typically take around seven to ten working days from the date the sample reaches the laboratory. Some providers offer a faster turnaround for an additional fee. NHS NIPT results timelines vary by trust, so ask your midwife what to expect if you have been referred through the NHS pathway.
What happens if my NIPT result is high risk?
A high-risk NIPT result does not mean your baby definitely has a chromosomal condition. You will be offered a referral to a specialist — usually a fetal medicine unit — to discuss your options. Diagnostic tests such as CVS or amniocentesis can provide a definitive result. Your midwife or genetic counsellor will support you through this process and help you understand your choices.
Further reading:
This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.
Last reviewed: June 2026
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