Non-Invasive Prenatal Tests: What are They and Why Might You Have One?

During pregnancy, you’ll be invited to various routine check-ups that help to ensure that you and your baby are well. These will typically include prenatal appointments and pregnancy ultrasound scans. If you’ve been identified as having a higher risk of having a baby with chromosomal abnormalities, you might consider having a non-invasive prenatal test.

A non-invasive prenatal test (NIPT) is a simple blood screening that looks at your DNA to analyse the risk of your baby having certain chromosomal conditions, including Down’s syndrome, Edwards’ syndrome and Patau’s syndrome.

Here, we’ll look at what a NIPT is, why you might consider having one, and when you would usually have this screening during your pregnancy.

What is a NIPT?  

A NIPT uses a sample of maternal blood, to test for DNA that originated in your baby’s placenta. From this sample we can identify whether you’re at a heightened risk of having a baby with a chromosomal (or genetic) condition. While a NIPT cannot determine for certain whether your baby has a chromosomal disorder, it can give you a very accurate indication of the likelihood of that outcome. 

Invasive genetic tests, such as amniocentesis or CVS, actually look at the baby’s own genetic make-up collected from their placenta or amniotic fluid, to determine with certainty  whether they have a chromosomal condition. However, the nature of these tests means they carry a small risk of miscarriage. 

If you are pregnant, it’s good to know that NIPTs have the advantage of being safe, quick, and easy, with no increased risk of miscarriage. In essence, their results can help you to decide whether you want to have any further, more invasive tests. 

What Happens During a NIPT?

During your appointment we’ll take a sample of blood from your arm, before sending it onto the lab, where a technician will examine the DNA in your blood. Once sent back to our clinic, we’ll call you with the results, along with a copy of your report. We’ll also review the results before sending the report to your doctor.

If you had your NIPT at the same time as your 12-week nuchal translucency  ultrasound (as we would recommend) we will then pair the results, to consider whether further testing would be recommended. If your results show that you are at a high risk of having a baby with a chromosomal condition, we will discuss further tests that might be beneficial for you, such as an amniocentesis or CVS, that are able to give you a definitive result that an NIPT cannot.

What Chromosomal Conditions Does a NIPT Screen For?

Things have come a long way in the past few years, and NIPTs can give information about a baby’s chromosomes that weren’t previously available to parents.

Depending on which NIPT you opt for, you can be sure that they will all screen for the most common chromosomal disorders: 

• Trisomy 21 (Down’s syndrome)
• Trisomy 18 (Edwards’ syndrome)
• Trisomy 13 (Patau’s syndrome)

Can a NIPT Identify Your Baby’s Gender?  

The majority of NIPTs available at our clinic can tell you whether you’re expecting a boy or a girl, so be sure to let your us know if you don’t want this information to be shared with you. 

What NIPTs Can You Have at Our Clinic?   

We offer a choice of prenatal screening tests from various companies, all of which use cutting-edge testing technology. At present, these are:

Illumina Test: Formally known as the Harmony Test, this screens for Down’s Syndrome, Edwards’ syndrome, and Patau’s syndrome, can determine sex, as well as screen for sex chromosome anomalies. 

MaterniT21: Similar to the Illumina test, it screens for Down’s, Edwards’ and Patau’s syndrome, sex chromosome anomalies, and can determine baby’s sex. Results are delivered within 5 days as low/medium/high risk of abnormality.

MaterniT Genome: The most comprehensive NIPT genetic screening test we offer, it examines each chromosome. It also screens for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome, along with other, rarer conditions. 

Delivered as either a “positive” or “negative” outcome for risk of abnormalities, these have a 99% accuracy rate if you receive a negative result. If you have a pregnancy that’s seen as high risk, this can give you the reassurance you need to plan your next steps.  

At What Stage of Pregnancy Would You Have a NIPT?    

You can visit our clinic for a NIPT from week 10 of your pregnancy. We recommend having the test, which involves a simple blood sample, at the same time as your early pregnancy ultrasound scan, at around 12 weeks. You can also choose to have an NIPT at your 20 week anatomy and anomaly scan.

Occasionally, will might offer you a NIPT even if you haven’t had a pregnancy ultrasound scan at our clinic. Please note thought that if you are less than 13 weeks’ pregnant, you’ll have to send evidence of your latest scan to us, which will have to have carried out within 4 days of your appointment with us. 

How Accurate is a NIPT? 

NIPTs have 99 percent accuracy when it comes to predicting the risk of Down’s syndrome, Edwards’ syndrome and Patau’s syndrome.

In comparison, the combined 12-week ultrasound scan and blood test has a much lower 75-80% accurate in predicting the risk of Down’s syndrome.

If an NIPT test does confirm that you are at high risk of having a child with a chromosomal condition, you might want to talk with your doctor about seeking a more definitive diagnostic test, such as CVS or an amniocentesis. 

An amniocentesis is still the only way you can be certain of whether or not your baby has Down’s syndrome, as it is a diagnostic test. However, the procedure involves using a very fine needle to withdraw some amniotic fluid around the baby, and therefore it does carry a small risk of miscarriage. (1 in 100). In comparison NIPTs are completely safe, but as screening tests they only evaluate the risk – rather than the certainty – of having a baby with a chromosomal condition.

Why Might You Consider Having a NIPT?  

The decision to have a NIPT test is a wholly personal one, and you should not hurry into making any choices that don’t feel right for you.

Certain women are seen as being at higher risk of carrying a baby with a chromosomal abnormality, such as mums-to-be who are older than 35, or who have previously had a child with a genetic condition.

As NIPTs evolve, it’s important to be given up to date information about the screening tests available to you. We can help to guide you at every stage.

If you do opt to have a NIPT, it’s totally normal to feel anxious about the results. Our doctors are here to guide you at every step and can discuss possible next steps depending on the outcome of your results.

Finding out about potential conditions as early on as possible can allow you to better prepare, and make plans that feel right for you and your family. 

Find Out More About NIPTs

If you would like to make an appointment for an NIPT please call 020 7244 4200 or make an appointment online.