What is NIPT Test in Pregnancy?

Being told you are pregnant is an overwhelming experience. You will have a million different emotions flooding through you, as well as lots of questions to ask. One of the first decisions you will have to make is if you want to have prenatal screening tests. The NIPT test has become one of the most popular, and talked about, screening tests that parents in the UK have. But what is it, and should you have one?

This guide takes you through everything you need to know about NIPT. We will explain how it works and what you can expect after you receive your results.

Understanding NIPT: The Basics

NIPT stands for Non-Invasive Prenatal Testing. It is a blood test that can tell you if your developing baby has certain chromosomal conditions. NIPT does this by analysing small fragments of your baby’s DNA that are found in your bloodstream during pregnancy.

It’s science, but in a nutshell: During pregnancy, the placenta releases tiny bits of DNA into your bloodstream. This is called cell-free DNA (cfDNA). Laboratories can test these fragments of DNA in your blood and can see whether or not your baby is likely to have conditions like Down’s syndrome, Edwards’ syndrome or Patau’s syndrome.

You can have the NIPT test from 10 weeks of pregnancy. This is when there is enough fetal DNA in your bloodstream for the laboratory to analyse with a high degree of accuracy. Results will usually be available within 5 to 10 working days, according to NHS guidance.

What Conditions Does NIPT Screen For?

The NIPT test in pregnancy primarily screens for three chromosomal conditions:

• Down's syndrome (Trisomy 21): occurs when a baby has an extra copy of chromosome 21. About 1 in every 1,000 babies born in the UK has Down's syndrome. People with Down's syndrome have intellectual disabilities and may have various medical complications involving the heart and digestive system.

• Edwards' syndrome (Trisomy 18): happens when there's an extra copy of chromosome 18. This is a more severe condition, and sadly, most babies with Edwards' syndrome do not survive to the end of pregnancy or die soon after birth.

• Patau's syndrome (Trisomy 13): results from an extra copy of chromosome 13. Like Edwards' syndrome, this causes severe developmental problems, and most affected pregnancies do not result in a live birth.

Some private NIPT tests also screen for sex chromosome conditions like Turner syndrome and Klinefelter syndrome. The test can also determine your baby's sex, though you can choose not to receive this information if you prefer.

How Accurate is the NIPT Test?

One of the main reasons NIPT has gained popularity is its high accuracy. Research published in peer-reviewed journals shows the test detects approximately 99% of Down's syndrome cases. Detection rates for Edwards' syndrome and Patau's syndrome are slightly lower but still above 90%.

The false-positive rate sits at around 0.1% to 0.2% for Down's syndrome. This means that out of 1,000 women who receive a high-risk result, only 1 or 2 will have results that don't match the baby's actual condition.

These figures make NIPT significantly more accurate than the traditional combined first trimester screening test, which has a detection rate of around 85% to 90% and a higher false-positive rate of approximately 5%.

At myGynaePlus, the specialist team understands that navigating prenatal testing can feel overwhelming. Having accurate information helps you make decisions that feel right for your circumstances.

NIPT vs Traditional Screening: What's the Difference?

The NHS currently offers the combined first trimester screening test as the standard screening option. This involves a blood test measuring placental hormones combined with an ultrasound measurement of the fluid at the back of your baby's neck (nuchal translucency).

So how does NIPT compare?

The detection rate of the combined test for Down's syndrome is approximately 85% and has a false-positive rate of about 5%. NIPT has better detection and false-positive rates: >99% and <1% respectively. The combined test provides a risk score (e.g. 1 in 150 or 1 in 1,000). 

If your result indicates a higher risk (1 in 150 or greater) you can now have NIPT as a follow-up test on the NHS. This pathway is designed to better determine which pregnancies would benefit from diagnostic testing, and so reduce the number of women undergoing invasive diagnostic tests unnecessarily.

Read More: What Is Gynaecologists

When Can You Have NIPT?

You can have the NIPT test from 10 weeks of pregnancy. You can't have it earlier because the fetal fraction (the amount of your baby's DNA in your blood) is too low for an accurate result.

On the NHS, the Fetal Anomaly Screening Programme guidance says NIPT can be done in singleton and twin pregnancies up to 21 weeks and 6 days.

The test is not suitable in certain situations. You cannot have NIPT if you:

• Are carrying triplets or higher multiple pregnancies

• Have had a blood transfusion in the past four months

• Have had transplant surgery, immunotherapy, or stem cell therapy

• Have Down's syndrome yourself or carry certain chromosomal conditions

• Have been diagnosed with cancer

Your midwife or consultant will discuss whether NIPT is appropriate for your specific circumstances.

What Happens During the Test?

The NIPT test is simple. A healthcare professional will draw blood from a vein in your arm – just as with any other blood test. There is no needle for the baby and no risk to your pregnancy.

The sample is sent to a specialist laboratory. Technicians will analyse the cell-free DNA, looking for an excess of DNA fragments from chromosomes 21, 18 or 13, which would indicate an increased risk of the related condition.

Your results will be available in one to two weeks. The report will indicate whether your baby has a low chance or high chance of having each condition screened.

Understanding Your NIPT Results

NIPT results come back as either "lower chance" or "higher chance" for each condition screened.

• Lower chance result: This is reassuring news. A lower chance result means your baby is very unlikely to have the conditions tested. The chance is typically less than 1 in 10,000 for most conditions after a negative NIPT.

• Higher chance result: This does not mean your baby definitely has a condition. It indicates increased risk that requires further investigation. The NHS recommends offering diagnostic testing to confirm the result.

• Inconclusive result: Occasionally, the laboratory cannot produce a result because there isn't enough fetal DNA in the sample. This happens in about 1% to 2% of cases. If this occurs, you may be offered a repeat blood test or diagnostic testing.

  
  

NIPT is a Screening Test, Not a Diagnostic Test

This is an important distinction. A screening test indicates the probability that something could be present. A diagnostic test indicates definitively whether it is or is not.

NIPT cannot tell you with 100% certainty that you or your baby has a chromosomal condition. Even though NIPT is highly accurate, it is possible to get a false positive or false negative result. There are a number of reasons for this:

• Confined placental mosaicism: happens when the placenta contains cells with a different genetic makeup than the baby. Since NIPT analyses DNA from the placenta, not the baby directly, this can lead to results that don't match the baby's actual chromosomes.

• Vanishing twin syndrome: occurs when a twin pregnancy becomes a singleton early on. DNA from the lost twin can affect NIPT results.

• Low fetal fraction: means there isn't enough baby's DNA in your blood for accurate analysis. This is more common in early pregnancy or in women with higher body weight.

  
  

What Happens After a High-Risk Result?

If your NIPT shows a higher chance result, your healthcare team will offer you diagnostic testing. The two main options are:

• Chorionic villus sampling (CVS) can be performed between 11 and 14 weeks. A small sample of placental tissue is collected using a needle or catheter. This sample contains the same genetic information as your baby and can confirm whether a chromosomal condition exists.

• Amniocentesis is performed after 15 weeks. A thin needle is inserted through your abdomen to collect a small amount of amniotic fluid. The cells floating in this fluid come directly from your baby, making it an extremely accurate test.

  
  

There is a small risk of miscarriage with either procedure. The current estimate is less than 0.2%. Many women are nervous before the procedure, and your healthcare provider will discuss exactly what will happen and answer any questions that you may have. myGynaePlus team has obstetricians with expertise to offer guidance on decisions regarding prenatal testing, and can walk you through every step. Our consultants can provide you with customized care during your pregnancy journey.

Accessing NIPT in the UK

In the UK, NIPT is available through both NHS and private pathways.

• NHS pathway: The NHS offers NIPT to women who have received a higher chance result (1 in 150 or higher) from their combined or quadruple screening test. In this case, the test is provided free of charge. Women with a previous pregnancy affected by trisomy 21, 18, or 13 may also be eligible through a specific pathway called R445.

• Private pathway: You can access NIPT privately regardless of your screening results. This option allows testing earlier in pregnancy without needing to wait for combined screening results first. Private NIPT typically costs between £300 and £500 depending on the provider and which conditions are screened.

  
  

Who Should Consider NIPT?

NIPT is suitable for most pregnant women from 10 weeks onwards. You might particularly consider it if:

• You want the most accurate screening test available for common chromosomal conditions

• You've had a previous pregnancy affected by Down's, Edwards', or Patau's syndrome

• You're anxious about your baby's health and want early reassurance

• You want to avoid invasive testing unless absolutely necessary

• You've received a higher chance result from combined screening

Some women choose not to have any prenatal screening, and that's a valid choice too. There's no right or wrong answer. What matters is making an informed decision that aligns with your values and circumstances.

The Emotional Side of Prenatal Testing

Prenatal testing can be an emotional topic. Some parents want to know as much information as possible about their baby's health. Others choose not to know, believing they would have continued their pregnancy whatever the result.

Waiting for results can be anxiety-inducing. If you're given a higher chance result, you may find the wait for diagnostic testing and confirmation particularly challenging.

If you're worried, speaking to a genetic counsellor can help. They are trained to explain test results and what conditions might mean for your child and family. Genetic counselors support you in making decisions about testing, without pressuring you one way or the other.

Whatever you decide, it's important to remember that prenatal screening is completely optional. No-one should feel pushed into having tests they don't want.

Making Your Decision

Choosing whether to have NIPT involves weighing several factors:

Think about what you would do with the information. Would knowing about a chromosomal condition change how you approach your pregnancy? Would you want time to prepare for a child with additional needs?

Consider your feelings about diagnostic testing. If NIPT shows a higher chance result, would you proceed with amniocentesis or CVS to get a definitive answer?

Discuss your options with your partner, if applicable, and with healthcare professionals you trust. Clinics like Mygnaeplus offer consultations where you can ask questions and explore your options without feeling rushed.

Looking Ahead

NIPT technology is still being refined. Scientists are working on being able to screen for more conditions, as well as even more accuracy. Cell-based NIPT, which tests intact fetal cells instead of loose DNA fragments, may be possible in the future. Cell-based NIPT has the potential to be used for diagnosis instead of screening.

At this time, NIPT is still a screening test. It is an incredibly accurate screening test for the most common chromosomal conditions, however. By understanding the benefits and the limitations of NIPT, you can make the best decision for you and your pregnancy.

Frequently Asked Questions

Is the NIPT test safe for my baby? 

Yes, the NIPT test is completely safe. It requires only a blood sample from your arm, with no needles or procedures anywhere near your baby. Unlike amniocentesis or CVS, NIPT carries no risk of miscarriage or harm to your pregnancy. The test simply analyses DNA fragments already circulating naturally in your bloodstream.

How early can I have NIPT done during pregnancy? 

NIPT can be performed from 10 weeks of pregnancy. Before this point, there typically isn't enough fetal DNA in your blood for accurate results. The test remains available throughout pregnancy, up to around 40 weeks, though most women have it in the first trimester for early reassurance.

Will my NIPT result tell me if my baby is healthy? 

NIPT screens for specific chromosomal conditions only, not all genetic problems or birth defects. A low-risk result is reassuring but doesn't guarantee a healthy baby. The test doesn't check for conditions like cystic fibrosis, spina bifida, or heart defects. Your 20-week anomaly scan and other tests screen for different aspects of your baby's health.

What should I do if I receive a high-risk NIPT result? 

A high-risk result means further testing is needed before any conclusions can be drawn. Your healthcare provider will offer diagnostic testing such as amniocentesis or CVS to confirm whether your baby actually has the condition. Many high-risk NIPT results turn out to be false positives, so try not to panic before diagnostic testing confirms the findings.

Does the NHS cover the cost of NIPT? 

The NHS provides NIPT free of charge if you've received a higher chance result (1 in 150 or higher) from combined or quadruple screening. You may also qualify if you've had a previous pregnancy affected by trisomy 21, 18, or 13. Outside these criteria, NIPT is available privately at your own cost, typically ranging from £300 to £500.