Non-invasive prenatal test (NIPT) – Harmony Test

The Harmony Prenatal Test is validated for use in singleton, twin, and IVF pregnancies, including egg donor pregnancies.


It’s a new blood test for Down syndrome, Edwards Syndrome and Patau Syndrome



Non-invasive prenatal testing (NIPT) is a new approach to testing whether a baby may be affected by a chromosome disorder. From a small sample of the mother’s blood, we are able to identify certain chromosomal conditions, such as Down syndrome.


During pregnancy, some of the baby’s DNA circulates in the mother’s blood stream. DNA is the substance that our chromosomes are made of and contains all our genetic information.


Usually, each human being has 46 chromosomes, arranged in 23 pairs. Occasionally, a baby is born with three copies of a particular chromosome, rather than two. This is known as a trisomy. The most common trisomies are Down syndrome, Edwards syndrome and Patau syndrome.


By analyzing the baby’s DNA found in the mother’s blood, we can detect whether or not there are abnormalities in the baby’s chromosomes.

What is Non-Invasive Prenatal Test (NIPT)?

Non-invasive prenatal testing (NIPT) analyses foetal ‘cell-free’ DNA circulating in the pregnant mother’s blood. Foetal cell-free DNA (cfDNA) results from the natural breakdown of foetal cells (presumed to be mostly placental) in the mother’s circulatory system. It clears from her system within hours of giving birth.

People usually have 46 chromosomes in each cell, but occasionally, extra copies of chromosomes can be present, as is the case in Down syndrome. Down syndrome is caused by an extra copy of chromosome 21. That is why it is sometimes called trisomy 21.

How is NIPT done?

The test is performed on a sample of the mother’s blood. About 10mls of blood is taken from the arm -  just like a normal blood test. The blood is then sent to the laboratory for testing.

How safe is NIPT?

As it is a simple blood test, NIPT carries no significant risk to you or your baby.

When is NIPT done?

From 10 weeks of pregnancy. Studies have shown that by 10 weeks there is adequate foetal cell free DNA present in the mother’s blood to conduct the test. The test is not recommended before that period. Therefore, it is essential that you have had an ultrasound scan and know the duration of your pregnancy and whether you are having one baby, twins, or more.

If you have already had a scan early on in your pregnancy, then on the day of the test (from 10 weeks onwards), another scan will be performed to confirm foetal activity and heartbeat.

How accurate is NIPT?

NIPT for Down syndrome is more than 99% accurate. This means that the test detects more than 99 out of 100 cases of Down syndrome, so there is only a very small chance that the test will not detect an affected pregnancy.


There is also a small chance that the test will incorrectly show that the baby has Down syndrome when it does not. This is known as a false positive result.


Even though the test is highly accurate, there is still a very small chance (around 1 in 300) of an incorrect result. Therefore, if the result of your NIPT predicts that the baby has Down syndrome, you will be offered an invasive test to confirm the result.

What types of chromosomal abnormalities does NIPT detect?

  • NIPT will detect the most frequent trisomies

A trisomy is caused by the presence of three copies of a chromosome instead of the regular two.

NIPT detects the following trisomies:

 • Trisomy 21, or Down’s Syndrome, is the most common trisomy.

 • Trisomy 18, or Edward’s Syndrome, has a high incidence of miscarriage or late foetal deaths

 • Trisomy 13, or Patau's Syndrome, is related to a high incidence of miscarriage. This chromosomal abnormality has a high foetal mortality rate.

  • Alterations in sex chromosomes

NIPT also detects alterations in the number of sex chromosomes, including:

• Turner Syndrome (45, X), the absence of an X chromosome in girls.

• Klinefelter Syndrome (47, XXY), the presence of an extra copy of the X chromosome in boys.

How long does it take to get the results from NIPT?

Usually results will be available within 5 – 10 working days

In a very small number of cases the laboratory may be unable to obtain your results. This might be because there was not enough of the baby’s DNA present in the blood sample to obtain a result. If this happens, then, the option of repeating NIPT will be explored.

What are the possible results?  ( You can see sample reports by clicking on the link)

  • Low probability

Your baby is very unlikely to have Down syndrome, Edward syndrome or Patau syndrome

  • High probability

It is very likely that the baby is affected with Down syndrome, Edwards syndrome or Patau syndrome. You will be offered an invasive test (see below) to confirm this result. This is offered because very occasionally, in around 1 in 300 cases, NIPT may not accurately reflect the result in the baby.

  •  Inconclusive result

As this is a new test we occasionally get an inconclusive or ‘unclear’ result. If we cannot detect a clear result, we will inform you and offer you another NIPT test.

  •  Failed result

Occasionally we get a failed result, if this happens we will offer you a repeat NIPT test at no additional cost.

How does NIPT compare with other screening tests currently offered during pregnancy?

The traditional screening test offered during pregnancy, which consists of an ultrasound scan and a blood test (or in some cases only a blood test), is less accurate than NIPT. The traditional test detects 84-90% of babies with Down syndrome.

What happens if the NIPT result predicts the baby has Down, Edwards or Patau syndrome?

If the NIPT result shows the baby has one of these chromosomal problems, you will be offered an invasive test. Invasive tests give a more definitive ‘yes’ or ‘no’ result as to whether the baby has Down syndrome or other common trisomy.

There are two types of invasive tests:

Chorionic Villus Sampling (CVS) – this is usually performed between 11 and 13 weeks.

Amniocentesis – usually performed from 15 weeks of pregnancy.

Both procedures involve using a fine needle to collect a small sample of either the amniotic fluid that surrounds the baby (amniocentesis) or a small sample of cells from the placenta (CVS). These tests carry a small risk of miscarriage of 0.5% to 1% in the UK. This means that for every 200 women who have a CVS or amniocentesis, one or two of them will miscarry due to the test.

What else should I consider before taking this test?

Before making a decision about NIPT, you may want to take some time to consider the test and discuss it with your partner. Think about how you might feel about the test results and how important the information would be for you and your family. Some couples feel that they may not continue with the pregnancy if a chromosome disorder was found. Others would continue whatever the results but would like to know in advance in order to prepare for the arrival of their baby.


I would always encourage you to have an ultrasound scan immediately prior to the harmony blood test.

Missed miscarriages commonly occur before 12 weeks’ gestation and you may not want the heartache of having a result from the harmony test if this has occurred.


I am unable to provide any refunds in these circumstances if you choose only the blood test and not the scan as well as the monies paid by you will be spent on the analysis of your blood sample


If you are unsure about anything, it can be helpful to discuss it with your healthcare professional.

Where can I get further information and support?

108 Harley Street, London, W1G 7ET, UK

Tel: 00 44 (0)207 563 1234

Email : info@mahanteshkaroshi.co.uk




Fill in the online questionnaire and you will be issued with a test request form


Attend the laboratory for blood collection at 10 weeks or later in pregnancy

Blood collection site

(Please produce the Test request form)

The Doctors Laboratory Patient Reception

76 Wimpole St,


London W1G 9RT


Lab results in as soon as 5-10 days or less

Smiling Pregnant Woman