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£389 / £429 with ultrasound scan



Non invasive prenatal testing

The Harmony test is a blood test that looks for whether your baby has Down’s Syndrome, Edward’s or Patau’s Syndrome. In these conditions there are 3 copies of certain chromosomes instead of 2 (“Trisomy”). The test looks at DNA from the baby that is present in the mothers bloodstream.

You can have this test at Somerset Early Scans from 10 weeks of pregnancy onwards.  



This is an extremely accurate screening test and has a higher detection rate (sensitivity) than the combined test currently offered by the NHS at 11-14 weeks. Harmony will detect over 99% of babies with Down’s syndrome. NHS screening identifies 84%. The Harmony test is also available earlier in the pregnancy, from 10 weeks onwards.

Many couples now choose to pay for a non invasive prenatal test (NIPT) such as Harmony because of the higher detection rate. 

Another reason for choosing an NIPT is after receiving a high chance result from the 12 week NHS screening test. If NHS screening suggests a baby is high chance for a trisomy condition, it has a 13% chance of being correct. Having a more accurate screening test means less chance of having to have an amniocentesis, a procedure with a 1 in 200 risk of miscarriage



Like all tests, the Harmony test has a small risk of being incorrect. It may report a low probability of the baby being affected when in fact the baby does have the condition.

Overall the Harmony test detects >99% of babies with trisomy 21,18 &13.

For trisomy 21 the detection rate is above 99%. Trisomies 18 and 13 are rarer conditions. The reported detection rates of these is 97% (T18) and 94% (T13).

There is also a chance of receiving a harmony test result that states a high probability of an affected baby when in fact the baby is not affected. Another way of looking at this is called the “positive predictive value”. The likelihood of a high chance result being correct (positive predictive value) depends on the background risk. If you have had a high chance result for Down’s syndrome from an NHS screening test or are in an older age group the positive predictive value will be above 90%. If you are low risk the positive predictive value will be much lower, again the risk depends on factors such as your age. One large study reported the PPV for low risk women to be 82% for Down’s syndrome and 37% of Edward’s, 49% for Patau’s.

Very occasionally these tests can pick up a problem in the mother, not the baby.

The Harmony test can also test for the gender of the baby however a recent report from the Nuffield Council of Bioethics has advised against its use for this without a medical reason.

It also has the capability to look at the number of sex chromosomes X and Y. An incorrect number of X and Y chromosomes can cause medical problems. However, limited numbers of babies with these conditions (sex chromosome aneuploidies) have been evaluated using Harmony so the accuracy of testing for this is uncertain. Therefore we do not recommend it.

More recently testing for diGeorge syndrome (22q11.2 deletion) has been introduced. The detection rate for this condition is 75%, meaning that 25% of affected babies would be reported as unaffected. Furthermore, the test will wrongly be reported as positive in 1 in 200 women. Again limited numbers of pregnancies have been tested for this so the performance is uncertain.  Therefore experts advise against using Harmony for this and we do not offer it as a company. If you are at high chance of having an affected pregnancy with diGeorge syndrome an invasive test (e.g. amniocentesis) is more accurate. 

Non invasive prenatal testing does not diagnose other genetic or structural diseases such as spina bifida. A negative result obviously does not guarantee a healthy baby.


When to test

Any time after 10 weeks of pregnancy. Before this point there is not enough DNA from the baby in the mothers bloodstream.


What will happen

We will see you to discuss the pros and cons of testing and take your consent if you decide to go ahead. We need to have accurate dating of your pregnancy so if you come before your NHS dating scan then a scan for viability & dating will be done followed by your blood test. Please note that it is essential to have had a dating scan before Harmony, the laboratory cannot process results without this. If you have had a scan in another service we can use the dates from that scan.

We will ask you how you would like to be informed of your results. The samples are sent by Royal Mail Business Post to The Doctors Laboratory in London, who process all the UK Harmony samples in house.

A result will be received within 10 days or less and you will be contacted by us within 24 hours. Our average time from appointment to result is currently 7 days.

In 3% of cases the sample cannot be processed due to it having insufficient DNA within it. In this case we will contact you to arrange repeat testing at no additional charge. This is more likely to happen if you are earlier in the pregnancy or overweight. So if your BMI is raised you may wish to come a little after 10 weeks.


Twins & IVF pregnancies

The Harmony test can be used for IVF pregnancies, including those with donor eggs.

It can be used in twin pregnancies for screening purposes but not to look at the sex chromosomes. It cannot be used in twin pregnancies where one twin has not been viable. It is also not validated for use in triplet pregnancies.


Positive tests

If you have a test result reported as high chance we recommend seeing an Obstetrician, or Fetal medicine specialist to discuss the pros and cons of having an invasive test such as an amniocentesis, to provide a diagnostic result. Or to discuss a plan for care during and after the pregnancy. We will seek your consent to contact your Midwife or Obstetrician on your behalf so that this can be arranged.

Due to the small chance of the harmony test result being incorrect it is not considered to be diagnostic.


Why book with us?

We believe in informed choices so we allow plenty of time for a full discussion with you at your appointment.

The clinician who saw you will personally phone you as soon as your results are available.

In the rare event of a high risk report, we will liaise with the NHS team on your behalf, to get you seen quickly.

More information

Information about the conditions
Down Syndrome www.downs-syndrome.org.uk
Edward and Patau Syndrome www.soft.org.uk
Turner Syndrome www.tss.org.uk
Klinefelter Syndrome www.nhs.uk/conditions/klinefelters-syndrome

Harmony Test


Harmony Test With Ultrasound Scan


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