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NIPT and the Harmony test, your helpful guide

Knowledge Hub

8 mins readFact Checked
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Written By:

Atif Riaz

Medically Reviewed By:

Mr M. Usman

Harmony Test
Harmony Test

What is the Harmony test?

The Harmony test, also known as Non-Invasive Prenatal Testing (NIPT), is a screening test that detects genetic abnormalities in a foetus during pregnancy. It is a type of genetic test that analyses foetal DNA, which can be found in the mother’s blood.

The test is one of the leading and advanced non-invasive prenatal pregnancy screening tests available for parents wishing to determine the probability of their baby having Down’s syndrome (Trisomy 21), Edwards’ syndrome (Trisomy 18) or Patau’s Syndrome (Trisomy 13).

The test has a higher positive predictive value as compared to the combined test, which means lower high probability results where the condition is not actually present.

What Does NIPT Mean?

NIPT stands for Non-Invasive Prenatal Testing. It is a screening test that can detect genetic abnormalities in a foetus during pregnancy. Unlike other prenatal tests, such as amniocentesis or chorionic villus sampling (CVS), NIPT is non-invasive, requiring no invasive procedures that could potentially harm the foetus.

NIPT is a relatively new test that has been developed in recent years and is considered a safe and accurate method of prenatal screening for certain genetic conditions.

NIPT is considered non-invasive and is completely safe and will not harm the pregnancy.

It involves obtaining a small quantity of the mother’s blood, just like a routine blood test, which is then analysed in a laboratory. The analysis focuses on fragments of DNA (cell-free fetal DNA) from the pregnancy that are floating within the mother’s blood. The results of the test are usually available within 5-10 working days. 

NIPT has been shown to have a detection rate of over 99% for Down’s syndrome with a high negative predictive value.


What does NIPT show?

As a pregnant mother to be, you will have your own DNA in your bloodstream as well as the DNA of your unborn baby. Your babies DNA is found in your blood in the form of small fragments circulating around called cell-free DNA fragments (cfDNA) from the fetal placenta. NIPT tests will analyse this cfDNA to calculate a probability of your baby having one of the screened conditions, commonly Down’s syndrome (known as Trisomy 21), Edwards’ syndrome (known as Trisomy 18) and Patau’s syndrome (known as Trisomy 13). The NIPT test can be extended further to determine fetal sex and to identify risk for sex chromosome anomalies. Some NIPT can also screen for other chromosomal abnormalities.  

It is a non-invasive test as it does not touch the fetus, placenta or amniotic fluid and is completely safe for the baby. A small quantity of the mother’s blood is collected, just like a routine blood test, and analysed. The analysis focuses on cell-free fetal DNA in the mother’s blood.

NIPT can be undertaken by many pregnant women who wish to have screening, however, it is advised that the test is a screening tool and is not a diagnostic test and may, in a very small percentage of women, be inconclusive.

How well does NIPT Perform?

NIPT has been shown to be highly effective in screening for Down’s syndrome with very high sensitivity and specificity.

It has been shown to have a detection rate of over 99% for Down’s syndrome for singleton pregnancies with an extremely low false positive rate, low negative likelihood ratio and high positive likelihood ratio. 

It has been reported to be very effective in assessing the risk for Down’s syndrome in twin pregnancies and identifies at least 90% of pregnancies where one fetus is affected by Down’s syndrome. 

Furthermore, NIPT carries a very small failure rate, where the risk assessment cannot be completed. However, approximately 50% of these cases will obtain a result from repeat testing.

The Combined / Quad Tests Offered by the NHS

The combined or nuchal screening test is offered by the NHS to all patients from 11-14 weeks pregnant and determines a background chance of the pregnancy being affected by certain conditions based on maternal age (Down’s syndrome, Edwards’ syndrome & Pataus’ syndrome). The Quad test will also screen for these conditions and is offered to women who have missed the combined test appointment, presented late to the hospital or changed their mind about screening having initially declined the combined test, however the sensitivity of this test is lower than the combined test.

The combined test is time specific and can not be performed before 11 weeks or after 14 weeks of pregnancy. 

The background chance increases substantially for women who are 35 years of age and over.  This increases the likelihood of receiving a high chance result from these tests for these women. Therefore due to the limitations of this test the positive predictive value is reduced which means those women that are over 35 years of age are more likely to receive a high chance result, even if their baby does not have any of the conditions. 

Does NIPT replace diagnostic tests such as amniocentesis and chorionic villus sampling (CVS)?

NIPT tests do not replace prenatal diagnostic tests such as amniocentesis and CVS because they are different sorts of tests. In general terms, non-invasive prenatal tests screen for chromosome abnormalities in patients who do not have any medical evidence of problems affecting their pregnancy at the time the test is taken. The test is carried out without directly sampling cells from the fetus or placenta. In contrast, amniocentesis takes cells from the amniotic fluid surrounding the baby, while CVS samples cells from the placenta. This process however is associated with a small risk of miscarriage. 

Invasive tests are usually performed later than NIPT. Non-invasive prenatal tests are very good at detecting an abnormal number of copies of individual chromosomes, but some types of chromosome anomalies cannot be identified. Examples include triploidy and changes that alter the structure of chromosomes. Amniocentesis and CVS offer the possibility of generating a complete karyotype (picture), allowing additional types of abnormality to be detected. 

Amniocentesis or CVS would normally be an option if recommended by a doctor. Such tests would be used to determine if an abnormality was present when non-invasive tests such as NIPT have indicated a higher risk of an abnormality.

Which other NIPT tests do you offer?

We offer a number of leading and cutting edge Non Invasive Prenatal Tests, including Harmony NIPT test, Neo 24 NIPT test and Panorama NIPT test. Further information about harmony is given on this page further below, just scroll down. To find out more about our other tests including Neo and Panorama as well how out NIPT appointments work then please click on one of the buttons here:

When can I have the Harmony test?

The test is available from as early as 10 weeks into the pregnancy. It is available for single, including donor or surrogate and twin pregnancies. You can also choose to find out the sex of your baby*.

The test can be performed for the majority of pregnant women, however is particularly recommended for

  • parents who wish to avoid unnecessary invasive testing, which carries a risk of miscarriage
  • women over 35 years of age
  • parents that have had a high probability result in their current or previous pregnancies 
  • confirmed chromosomal condition in a previous pregnancy

Please note that blood thinners can increase the possibility of receiving no results.

How is the test Performed?

The test involves a simple and safe blood test whereby a small quantity of blood is collected from the mother, usually via a vein in her arm. The blood is then sent to the lab and analysed for cell-free DNA (cfDNA), circulating fragments of fetal DNA.

These are derived from the maternal placenta, the organ providing nutrition to the baby, and are circulating in the mother’s bloodstream. The results determine if there is a high or low probability of a baby having one of the 3 screened conditions; Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. 

The test can be performed as early as 10 weeks into the pregnancy, and results are typically available within a few days.

Where are the results analysed?

The test is processed and analysed in the UK. 

What do the Results Show?

The results of the Test show whether the foetus is at an increased risk of having certain genetic abnormalities. The test is highly accurate, with a false-positive rate of less than 1%.

The test can detect a variety of genetic abnormalities, including Down syndrome, Edwards syndrome, Patau syndrome, and certain sex chromosome abnormalities. In addition, the Harmony Test can also detect the sex of the foetus.

If the test results indicate an increased risk of a genetic abnormality, further testing may be recommended to confirm the diagnosis. This may include a more invasive test, such as amniocentesis or CVS.

How can I book?

To book the test please click here

Who created the test?

The Harmony prenatal test is backed by Roche, A pioneer in healthcare for over 120 years.

  • Ariosa Diagnostics, Inc., the creator of the test, started offering the test in 2012
  • Ariosa Diagnostics joined Roche, a healthcare partner with a clinical mindset, in 2014
  • Harmony prenatal is a Roche offering.
Harmony Test Logo

What else can the Harmony test do?

In addition to screening for the conditions listed above, you and your healthcare provider can discuss which additional options might make sense for your pregnancy.

Fetal sex – So you know whether your baby is male or female (also available with twins)

Monosomy X – Also called Turner syndrome, a condition where a female is missing an X chromosome and as a result, may have heart, endocrine, and learning problems

Sex Chromosome Aneuploidy – Differences in the number of X and Y chromosomes which can result in certain learning and/or behavioural challenges in addition to other health issues.


Harmony is a safe and accurate screening test that can detect genetic abnormalities in a foetus during pregnancy. It is a non-invasive test that involves taking a sample of the mother’s blood and analysing it for the presence of foetal DNA. The test can detect a variety of genetic abnormalities, and if the results indicate an increased risk, further testing may be recommended to confirm the diagnosis. Overall, the test provides valuable information that can help parents make informed decisions about their pregnancy and the care of their child.

*Please note that in some instances, the NIPT test may not determine the sex.  In monochorionic (identical) twin pregnancies, NIPT can confirm the sex of each twin as it will be the same. For dichorionic (non-identical) twin pregnancies, Harmony can confirm if there are 2 girls, but can only confirm the presence of 1 boy.

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