Harmony prenatal test

The Harmony test, or NIPT test is available at TFP 92 Harley Street from week 10 of pregnancy, and is designed to give you peace of mind when you need it most.

mother and son smiling, leaf

Our service includes the Harmony blood test and a scan, allowing you to see your baby, in the comfort of our first-class facilities.

Harmony Test appointments are usually available within 24 hours and are performed by a Senior Sonographer or Radiographer. Results are available in 5 working days, giving you clarity and accuracy without delay.

What is the Harmony prenatal test?

The Harmony test is a non-invasive prenatal testing (NIPT) that can be carried out after 10 weeks of pregnancy. It is a blood test that analyses DNA from the fetus, called cfDNA, which circulates in the mother’s blood.

This test has no risk to the baby and has a detection rate of up to 99% for Down's Syndrome. The Harmony or NIPT test can also detect Edwards' Syndrome (up to 97% detection rate) and Patau Syndrome (up to 94% detection rate).

What is cfDNA?

Cell-free DNA (cfDNA) results from the natural breakdown of fetal cells (presumed to be mostly from the placenta) and clears from the mother's system within hours of giving birth.

During a pregnancy, cfDNA can be tested to give the most accurate screening approach in estimating the risk of a fetus having a common chromosome condition sometimes called a trisomy. This occurs when there are three copies of a particular chromosome instead of the expected two. The test looks to detect the following trisomies:

  • Trisomy 21 is the most common trisomy at the time of birth. Also called Down’s syndrome, it is associated with moderate to severe intellectual disabilities and may also lead to digestive disease, congenital heart defects and other deformities.

  • Trisomy 18 (Edwards' syndrome) and Trisomy 13 (Patau syndrome) are associated with a high rate of miscarriage. These babies are born with severe brain abnormalities and often have congenital heart defects as well as other birth defects. Most affected individuals die before or soon after birth, and very few survive beyond the first year of life.

  • Sex chromosome conditions. The sex chromosomes (X and Y) determine whether we are male or female. X and Y chromosome conditions occur when there is a missing, extra, or incomplete copy of one of the sex chromosomes. This test may not be applicable to everyone and should be discussed with a consultant. This option is not available for twin pregnancies.

How accurate is the Harmony Test?

Clinical studies have shown that the Harmony test offers an exceptional level of accuracy in diagnosing chromosomal conditions such as Down's Syndrome. Conventional screening will detect approximately 70-80% of pregnancies with Down's syndrome. The Harmony test will detect over 99%.

Although prenatal screening tests can carry a false negative or positive ratio, Harmony has a false positive rate of less than 0.1% compared to 5% with conventional screening. Furthermore, as the Harmony test is non-invasive it poses no risk to the fetus, unlike other invasive tests such as in amniocentesis or chorionic villus sampling (CVS).

Although the Harmony test is highly accurate in the diagnosis of several key chromosomal conditions, it does not rule out all fetal abnormalities.


Is there any risk to my baby?

The Harmony test is non-invasive: it involves taking a blood sample from the mother’s arm, from 10 weeks of pregnancy. The pregnancy is not put at risk of miscarriage, or from other negative outcomes that are associated with invasive testing procedures such as amniocentesis.

Who is the Harmony test suitable for?

The Harmony test is suitable for a wide range of pregnancies. For women undergoing IVF treatment, or having a child in later life, a prenatal test offers an exceptional level of accuracy in the diagnosis of congenital conditions, and can provide great reassurance. The Harmony test is suitable for:

  • All single pregnancies including IVF pregnancies

  • Twins if conceived naturally

  • Twins by IVF/Donor

The Harmony test can also be used to find out the sex of your baby. This part of the test is suitable for:

  • Single pregnancies only (not twins)

  • Twin pregnancies if the foetuses are both female. In the case of a male, only one foetus can be sexed.

  • All IVF single pregnancies regardless of whether the egg is provided by a donor or patient.

The Harmony prenatal blood test is available for pregnant women at Harley Street from week 10 of pregnancy.

Can I get a Harmony test in London?

You will have the test in the comfort of our private clinic on Harley Street, London.

What does the Harmony test cost?

The Harmony test service at 92 Harley Street costs £550. This 40 minute appointment with a Senior Sonographer or Radiographer includes an ultrasound scan followed by the Harmony blood test, with results available in 5 working days. Our Harmony appointments are usually available within 24 hours.

To book your Harmony Test, contact us.

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