7 April 2019

What is non-invasive prenatal testing (NIPT)?

Pregnancy can be the most wonderful time of life, full of feelings of promise, excitement and, for many people, a time of glowing health and a sense of wellbeing. However, it is also a time of heightened anxiety and fears, some of them non-specific and irrational (but understandable) about a specific danger or risk. For women in an older age group, who know they are in a higher-risk category, this is even more understandable.

In this regard, our IVI blog article examines a new method of prenatal testing, a targeted and highly effective technique which can have a huge impact on specific fears, such as the risk of a baby having chromosomal abnormalities such as Down syndrome, among others. This is non-invasive prenatal testing, or NIPT. We explain what exactly it is, how the NIPT test works, how accurate you can expect it to be, and how IVI can help.

What exactly is non-invasive prenatal testing?

NIPT tests are also known as cell-free foetal DNA blood tests. They are the most comprehensive non-invasive prenatal tests that exist. They detect the presence of anomalies affecting chromosomes 21, 18 and 13, (including Down, Edwards and Patau syndromes), plus the most common anomalies affecting the sex chromosomes X and Y.

For very specific cases, and when the obstetrician request it, there are also more advanced cell-free foetal DNA tests, with the ability to detect other trisomies related to first trimester miscarriages, and which can also identify microdeletions related to other important genetic syndromes.

In the past, tests for genetic abnormalities, such as the Down syndrome, were invasive. That means they involved taking a sample of amniotic fluid from inside the amniotic sac or from the placenta and this in turn carried with it a small risk of causing a miscarriage. Thus, the decision on whether or not to undergo such a test could be a stressful one. The most important and unique feature about NIPT is the ‘non-invasive’ part: it is completely safe for the growing foetus and involves nothing more than a routine blood sample taken from the woman in the conventional way.

 

What is the difference between NIPT and prenatal diagnostic tests?

NIPT is a prenatal screening analysis, which examines DNA from the baby’s placenta in a sample of the mother’s blood to identify whether she is at increased risk of giving birth to a child with a genetic disorder. A screening process like the NIPT test cannot determine with absolute certainty whether the baby actually has a chromosomal disorder, only the likelihood of having that condition. However, in spite of this, prenatal testing is highly accurate.

The results of an NIPT screening would help you and your medical adviser decide on the next course of action, including whether to not do anything else or to undergo a diagnostic test like chorionic villus sampling (CVS) or amniocentesis. These genetic tests analyse the baby’s own genetic material, collected from the amniotic fluid or placenta, and show with 100 percent certainty whether a baby has a chromosomal abnormality. But of course, unlike non-invasive prenatal testing, they carry the small risk of miscarriage mentioned above.

 

Who is prenatal testing for?

Anything that can help to alleviate the anxieties that seem to go hand in hand with the more positive feelings associated with pregnancy can only be a good thing, and any pregnant woman can have the NIPT test. If it helps to reduce anxiety or alleviate any specific worry then it’s well worth it. So, the test is recommended for all women who want to rule out the presence of chromosomal abnormalities in the foetus without putting their pregnancy at risk. However, this test is especially suitable for women with a high risk of chromosomal abnormalities following 1st trimester screening, which consists of hormone analysis and the ultrasound scan, or who have had a previous Down syndrome pregnancy. This test is also recommended in the case of a twin pregnancy.

In the past, NIPTs were mainly recommended for women at high risk of carrying a baby with a chromosomal abnormality, such as women over the age of 35 or those who have  previous personal or family history of  genetic disorders. These days, however, the recommendation is usually that all pregnant women, regardless of age or risk level, discuss all the screening options with their advisers to decide which, if any, are most appropriate.

 

How does NIPT detect Down syndrome and other genetic conditions?

Let’s have a quick recap on what Down syndrome is and what causes it. People normally have 23 pairs of chromosomes in each cell and each chromosome is made of a coil of DNA containing our genes. These give instructions to our body to tell it how to work. Down syndrome occurs when a person has an extra copy of chromosome 21. The presence of this extra genetic information is what causes the physical and mental characteristics of people with Down syndrome.

The NIPT test for Down syndrome works by analysing the DNA fragments present in the maternal blood plasma. Most of this comes from the mother, but in addition about 10%-20% of it comes from the unborn baby. Therefore, by analysing all the DNA sequences linking to individual chromosomes, the total amount of chromosome 21 in the mother’s blood can be compared with the amount of the other chromosomes. If the baby has Down syndrome, there is slightly more chromosome 21 than expected, showing that there is more of this particular chromosome in the sample than normal. In this way, the test results in a very accurate prediction.

 

How accurate are the results of NIPT?

Because cell-free foetal DNA tests use the latest sequencing technology to analyse foetal DNA in relation to maternal DNA, certain anomalies can be detected with great precision and reliability. These tests have an accuracy of up to 99.7% in foetuses with Down Syndrome, as well as other frequent anomalies affecting chromosomes 18, 13, X and Y with the same level of reliability. Since false negatives are rare, this high statistical level of accuracy should be enough to offer real reassurance to women and couples and leave them free to enjoy the positive aspects of pregnancy.

 

Non-invasive prenatal testing: How IVI can help

Why not take a look at the video about IVI, in which we introduce ourselves and the range of services we offer, on the IVI YouTube channel? In the case of NIPT, this type of test can be performed and the results can be obtained within 3 days from receipt of the blood sample. We know how a long wait for results can heighten anxiety levels, and so this ability to produce a speedy result is a really important factor in helping to provide reassurance.

We would encourage anyone who may be interested in this particular test, or any other of the tests and techniques that we offer, to browse our website in order to familiarise themselves with the current state of affairs. Since medical research and advancements in the field of prenatal testing and all aspects of pregnancy care and assisted fertility are progressing and developing constantly, we rely on our website to bring you the latest information, statistics and articles of interest in the field.

 

IVI: our record and results

Our success rates in the field of assisted reproduction are consistently good, as is our forward-looking approach to new technologies and techniques. We cover a range of services from traditional treatments such as artificial insemination and in vitro fertilisation to more innovative techniques such as sperm microinjection and the Embryoscope®, which IVI participated actively in developing. We are one of the European centres with the best pregnancy rates and overall, 9 out of 10 couples who put their trust in us achieve their objective. You can see our independently audited clinical results for yourself, by downloading them from our website.

 

It’s easy to contact us at IVI

We know it can feel like a big step to make that first contact, but when you feel ready, go ahead, and you will probably find it a lot more stress-free than you feared! You could get a feel for what to expect from your first appointment by taking a look at the First Consultation video on our YouTube channel. After that, if you feel the need to discuss any aspect of fertility, infertility, assisted reproduction or the sort of prenatal testing that we’ve covered in this article, give us a call. You can reach us on 08 000 850 035 if you’re calling from the UK or on +34 960 451 185 from all other countries. Alternatively, you could complete our online contact form and a specialist adviser will get back to you.

You’ll be in the best hands right from the beginning.

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