NIPT – Non Invasive Prenatal Testing

We combine advanced NIPT for Down’s syndrome and chromosomal anomalies with our expert ultrasound scan to check your baby’s health as early as possible.

Our Expert Scan & NIPT tests are currently the most competitive with prices starting from £380.

10 weeks is the best time to perform Harmony or Invitae NIPT

At London Pregnancy Clinic, we offer the most advanced Harmony and Invitae NIPT packages offering not only screening for Down’s, Edward’s and Patau’s Syndromes, but also a comprehensive structural screening of your baby from 10 weeks.

We recommend booking your NIPT along with our revolutionary 10 week scan. 

If you are past the 10-11 week mark, visit our Scans Page to find out which fetal scan you will be having along with NIPT, as the test is available from 10-24 weeks.

Our NIPT + Early Anomaly Scan always incorporates chromosomal anomaly and structural screening from as early as 10 weeks

NIPT at London Pregnancy Clinic

  • Most accurate Down’s Syndrome screening test currently available

  • Advanced structural and chromosomal screening from 10 weeks: 3 chromosomal syndromes (by NIPT) + at least 10 severe structural anomalies (by scan)

  • Two advanced tests to choose from: Invitae NIPT £380 and Harmony Test £540

  • Scans and NIPT appointment with our Fetal Medicine specialist doctors with extensive NHS and international experience.

  • Same day, evening, and weekend appointments
  • Harmony NIPT results in 3-5 working days (95% of the cases)

  • Optional Gender Reveal included in the price 

  • Latest 3D/4D ultrasound technology

  • 5* rated service on Google, Trustpilot & Doctify
  • Scan report, videos and images sent straight to your smartphone

NIPT Testing Explained

What is NIPT (Non-Invasive Prenatal Screening)?

Non-Invasive Prenatal Screening is an advanced screening test predominantly for 3 chromosomal anomalies:

  • Down’s Syndrome (Trisomy 21 – >99% detection rate)
  • Edward’s Syndrome (Trisomy 18 – 97.4% detection rate)
  • Patau’s Syndrome (Trisomy 13 – 93.8% detection rate)

The test is highly accurate with false positive rates <0.1% for all 3 trisomies. Detection and false positive rates are calculated at a risk cut-off of 1/100. The Fetal Sex detection is >99% accurate.

10 weeks is the best time to perform NIPT

10 weeks is the best time for your NIPT because:

  1. You prefer to be reassured regarding Down’s syndrome as early as possible
  2. We perform your earliest fetal structural anomaly scan at 10 weeks which will exclude severe not-chromosomal defects
  3. In case of no-call NIPT results of the test you have plenty of time to to retake the test and have alternative screening for Down’s syndrome by Combined Test
  4. In case of high-chance NIPT results you can perform CVS (invasive test) to confirm or exclude the chromosomal problem at earliest possibility (usually at 11-12 weeks).
  5. In case of an abnormal finding in our 10 Week Scan, we will assist you in an urgent referral to Fetal Medicine Unit without wasting your time or money for inappropriate NIPT. It is well-recognised that NIPT is unsuitable test in the case of structural fetal anomaly
Tests available at London Pregnancy Clinic

‘Harmony Test‘ is a brand name for Roche’s NIPT and was a pioneer in the field, the analysis performed in London by TDL Genetics.

‘Invitae NIPS’ is a test developed by Invitae in the US. NIPS is becoming a more common technology allowing new entrants with impressive validation data and cheaper testing cost.  

Please find a comparison table between the tests below. 

How is the test performed?

Our Fetal Medicine doctor will initially conduct a anatomical examination of the baby to check for structural anomalies and take some measurements for the NIPT test. 

Once the clinician is satisfied with the baby’s normal structural examination, they will proceed with a consultation about NIPT to answer your questions about every aspect of the test. 

Finally, our friendly phlebotomist will take a blood sample from the mother’s arm – just like any routine blood test you may have done elsewhere.

Our staff then process the blood samples and will send them to the lab soon after your appointment. Now all there’s left to do is to wait for a call from us!

Why do I need to have an ultrasound scan with NIPT?

Ultrasound is a vital part of fetal screening. The laboratory requires a confirmation of viability and gestational age by the clinic submitting each NIPT

NIPT is a highly effective screening test for 3 chromosomal anomalies, however it is unable to screen for structural anomalies such as heart or brain defects which are more common and often more serious than Down’s Syndrome.

Here at London Pregnancy Clinic we specialise in early detection of fetal anomalies, the fetal heart and the fetal brain. We can detect some most severe fetal anomalies as early as at 10 weeks. Visit our Scans Page to find out which scan you will be having along with NIPT. Generally, we believe that our 10 Weeks Scan is the best option.

10 Structural Anomalies we Screen for at 10 weeks

With our expertise and technology we are able to screen for structural anomalies from 10 weeks (approximate prevalence in the first trimester):

  • Acrania (1:1,000)
  • Alobar Holoprosencephaly (1:1,300)
  • Spina Bifida (1:2,000)
  • Absence of arms, hands, legs or feet (1:2,000)
  • Encephalocele (1:5,000)
  • Exomphalos (Omphalocele) with liver (1:3,500)
  • Amniotic Band Anomaly (1:7,000)
  • Body Stalk Anomaly (1:7,500)
  • Sirenomelia (1:60,000)
  • Conjoined Twins (1% of monochorionic twins)

In comparison, the prevalence of the chromosomal conditions screened for by NIPT:

  • Down’s Syndrome (1:700)
  • Edward’s Syndrome (1:1400)
  • Patau’s Syndrome (1:5000)

If you take the test at 12+ weeks we are able to screen by ultrasound for >100 structural fetal anomalies, however we may lose few advantages of early NIPT.


£ 380


>10 weeks

Turnaround time
5-9 working days

Laboratory Location

Down’s Syndrome (T21)
Sensitivity >99.99%
False + ve rate <0.1%

Edward’s Syndrome (T18)
Sensitivity >99.99%
False + ve rate <0.1%

No Call Results

Fetal Fraction Cutoff

Vanishing Twins Eligibility*

Sex Chromosome Aneuploidy**

For an additional $500 payable to Invitae

Optional Gender Reveal
Yes (>99% accuracy)

Harmony NIPT

£ 540


>10 weeks

Turnaround time
3-5 working days

Laboratory Location
London, UK

Down’s Syndrome (T21)
Sensitivity >99.3%
False + ve rate <0.1%

Edward’s Syndrome (T18)
Sensitivity >93.8%
False + ve rate <0.1%

No Call Results

Fetal Fraction Cutoff

Vanishing Twins Eligibility*

Sex Chromosome Aneuploidy**


Optional Gender Reveal
yes (>99% accuracy)

General Notes:

For Invitae blood test $99 payable directly to the lab. Your bank may charge you small additional currency transaction fees.
The data taken from the clinical data published by Roche and Invitae.

* Vanishing twin is a situation with twin pregnancies when the embryo or fetus in one of the sacs fails to develop or dies at the early stages of pregnancy. 

** Not routinely offered. Sex chromosome aneuploidy panel NOT recommended due to limited clinical validation data, a much higher false positive rate and inconclusive results. The positive or inconclusive results of the test usually NOT covered by NHS and you may require private genetic counselling and possible private invasive test (CVS or amniocentesis) for your own expense. 

Frequently Asked Questions

Your questions answered

What is NIPT? What is the Harmony test? What is Invitae NIPS?

Non-Invasive Prenatal Testing (NIPT) or alternatively Non-Invasive Prenatal Screening (NIPS) is a screening method for determining the chance that a baby will be born with Down’s syndrome or other chromosomal anomalies. NIPT is based on the assessment of small DNA fragments from a baby’s placenta (named ‘cell-free DNA’ or ‘cfDNA’) that are disseminated in the blood of every pregnant mother. Placental cfDNA is usually identical to the DNA of the baby and testing it provides an opportunity for early detection of particular chromosomal anomalies without harming the baby.

Harmony Test is a well known NIPT brand by Ariosa/Roche. Harmony Prenatal Test is a trade name of the cfDNA test. We have experience of using Harmony for many years. Currently there are many other brands of NIPT, which provide similarly reliable results. After careful consideration we have chosen our second NIPT provider which is Invitae NIPS.

Invitae NIPS (non invasive prenatal screening) is an advanced NIPT, which has lower sample failure rate comparing with Harmony Test and its price is much more affordable for the future parents. The limitation of Invitae is its long results reporting time (up to 7 working days) which is a result of sample shipping to California based Lab. 

Although cfDNA is a relatively new genetic test, it has been proven to be superior to any other screening tests for Down’s Syndrome, including the Combined Screening Test (CST) used by the NHS. However, NIPT can detect a relatively small proportion (about 15%) of all fetal anomalies, because the vast majority of fetal anomalies are physical (structural) and not chromosomal.

NIPT is a screening test, meaning that NIPT cannot give a definitive answer about whether a baby has Down’s syndrome or other tested chromosomal conditions. If the results are positive (high chance) follow-up invasive testing is needed to get a definite diagnosis. Any invasive testing carries a small risk of miscarriage.

Why choose Invitae NIPS?
  • Advanced genetic technology
  • Less no call results (<2%)
  • Better fetal fraction cutoff (1%)
  • Works on pregnancies with vanishing twins
  • Option of microdeletions screening (an additional $500 payable to Invitae)
  • Affordable ($99 for the blood test)
Why choose the Harmony test?
  • The most popular NIPT brand in London
  • Clinically proven reliability for Down’s syndrome screening 
  • Fast test results in majority of the cases just 3-5 working days
  • Performed in laboratory located in London
  • Option of having fetal sex reveal without running generally not recommended sex chromosome aneuploidy panel
What are the limitations of Invitae NIPS?
  • Long turnaround time: up to 10 working days. It is due to transfer time to California, US based Invitae Laboratory.
  • Sex chromosome aneuploidy panel is NOT recommended due to limited clinical validation data, a much higher false positive rate and inconclusive results. The positive or inconclusive results of the test usually NOT covered by NHS and you may require private genetic counselling and possible private invasive test (CVS or amniocentesis) for your own expense.
What are the limitations of Harmony Test?
  • Higher cost
  • High sample failure rate: 3% suggested by Lab, however real failure rate is more than 5% by our clinical audit of the Lab performance
  • Does not work in pregnancies with vanishing twin phenomena
What are Nuchal Translucency/Combined Test offered by NHS performance figures?

Currently NIPT is not routinely offered by the NHS.

The Nuchal Translucency (NT) thickness measurements scan was developed in the 1990s, and at the time was the best screening option for Down’s Syndrome offering about 62% accuracy and 5% false positive rate. The NHS now offers the ‘Combined Test’ at 11-14 weeks which includes a Nuchal Translucency scan along with a blood test (for PAPP-A and HCG proteins) with improved the accuracy of 81% and false positive rate of 4.5%.

NIPT was first introduced in 2011 and was shown to have superior accuracy to the Combined Test with 99.99% detection rate and sub 0.1% false negatives. Please note, we still recommend following through with your NHS antenatal appointments, they are important for the continuity of your pregnancy care.

Which chromosomal conditions does the Harmony test at London Pregnancy Clinic cover?

We offers NIPT for:

  • Down’s syndrome (T21)
  • Edwards syndrome (T18)
  • Patau syndrome (T13)
  • fetal sexing (Harmony NIPT)

At London Pregnancy Clinic we DO NOT routinely offer NIPT for the following conditions, however you can discuss those options with our doctors:

  • sex chromosome abnormalities
  • 22q11 deletion
  • other microdeletions
  • triploidy
NIPT for sex chromosome abnormalities and microdeletions

Some biotechnological companies/manufacturers of NIPT including Invitae NIPS test, which London Pregnancy Clinic offers, have launched commercially available products aiming to screen for sex chromosome abnormalities and microdeletions (including 22q11 del).  

Although the tests are technologically advanced, the peer-reviewed validation data for those tests is patchy and the accuracy is inferior to the tests for T21, T18 and T13.

In the UK, the NHS considers the use of those tests controversial and as such unlikely to accept a ‘high probability’ test results as a referral for further invasive testing or genetic counselling.

In London Pregnancy Clinic we strongly recommend to perform Invitae NIPS test without options of sex chromosome abnormalities (sex chromosome aneuploidy panel) and microdeletions.

Why 10 weeks is the best time to perform NIPT?

We recommend to take the NIPT along with our comprehensive early anomaly scan (10 Weeks Scan) as soon as possible – 10 weeks. Early detection of either chromosomal or structural anomalies allows more time in terms of pregnancy management for those conditions. If your sample fails you have plenty time for redraw.

If you’re unsure about the age of your pregnancy, we strongly recommend to perform Viability Scan with us at around 7-8 weeks of your gestation. Viability scan will date your pregnancy and we can arrange earliest possible appointment for your NIPT.

If you prefer not to have Viability Scan please allow a couple of days after the 10 weeks mark to avoid repeat appointments for drawing the bloods. You can also miss all the advantages of 10 Weeks Scan, because your baby will be too young to have proper early anomaly scan. 

In theory, NIPT is available from 10-40 weeks, but it is strongly recommended to take the test in the first trimester, as the pregnancy management options in the second trimester can be very limited. 

How are the NIPT results communicated?

Following your scan appointment, you will receive a detail scan report from our doctors, as a hard copy and a PDF version sent to you via our secure cloud system Tricefy.

As soon as we receive your NIPT test results from the laboratory, our clinician reviews the test results and signs them off. One of our friendly clinical staff will then contact you via a phone call to interpret the test results. We will then send you a soft copy of the test results via Tricefy.

Who is NOT eligible for Harmony Test?

The Harmony Prenatal Test is not validated and can not be use for use in pregnancies with:

  • a history of or active malignancy
  • a pregnancy with fetal demise (in this case it is possible to perform Invitae NIPS)
  • a pregnancy with triplets, quadruplets or higher order
  • a history of bone marrow or organ transplants
  • mosaicism for the parents
  • maternal aneuploidy (chromosomal abnormality)
  • in women under the age of 18

Please note that IVF pregnancies are eligible for Harmony Test

What is the processing time for the NIPT blood test?

Turnaround time of Harmony Test in London is about 3-5 working days in 95% of the cases. For Invitae, the tests are sent over to the US and can take up to 5-7 working days.

From our clinic the sample is securely collected by a specialist medical courier service.

See below information about Harmony test no-call results and need to redraw the blood sample (no additional cost.)

What are the advantages of NIPT?

The main advantages of NIPT are related to Down’s syndrome (T21) screening.

They are:

  • early testing from 10 weeks
  • high negative predictive value for T21
  • high detection rate for T21
  • low false-positive rate for T21
What are the limitations of NIPT?

As any screening test NIPT has some disadvantages.

Here there are the most significant NIPT limitations:

  • relative high cost of the cfDNA test (Harmony Test)
  • whilst a very sensitive screening test, it is not diagnostic
  • cannot detect ANY physical (structural) anomaly
  • very limited effectiveness for the babies that have increased nuchal translucency (NT) thickness or physical (structural) anomaly
  • processing time of up to a week (or longer in 5% of the cases) or even 10 days for Invitae NIPS
  • failure to return a result in up to 5% of women (‘no-call’ results) which is more common for Harmony Test
I have never heard about Invitae NIPS, should I choose it?

The main advantages of brand new Invitae NIPS comparing with other NIPT providers are:

  • $99 (around £80) test cost which is paid directly to the Invitae Laboratories. This transparent price solution makes our combination of expert ultrasound scan and NIPT to be the most advanced and cost-effective option for early reassurance of the parents
  • Fewer no-call results (<2%) than other NIPT providers
  • Low fetal fraction cull-off (only 1%)
  • Pregnancies with vanishing twin phenomena* can be tested by Invitae NIPT
  • Additional options for Microdeletions Screening like Di George Syndrome (1p36.3-p36.2, 4p16.3-p16.2, 5p15.3-p15.1, 15q11.2-q13.1 and 22q11.21) for test price $500 and Sex Chromosome Aneuploidies (Turner syndrome and others) for the price of the regular test. Please note that Microdeletions and sex chromosome options are NOT recommended by professional medical bodies and their screening is NOT included in NHS fetal anomaly screening program. Those tests have relatively high chance for false-positive, inconclusive, and false-negative results, which can increase the chance of you having an unnecessary invasive testing with risk of miscarriage, financial loss for NHS-uncovered genetic service and anxiety or false reassurance. 

 The main disadvantages of Invitae NIPS are:

  • Longer turnaround time of 5-7 working days because of blood sample transfer to North America-based Invitae Laboratory
  • No gender reveal option without having full screening test for sex chromosome abnormalities.
What if my NIPT results show high chance for a chromosomal anomaly?

In case the NIPT result is high chance for Down’s / Edward’s / Patau’s syndromes (trisomy21 / trisomy18 / trisomy 13) our doctor will contact you and explain the further steps we advise to take. We will most likely arrange a referral to your NHS Fetal Medicine Unit for further counselling and possible diagnostic test such as CVS or Amniocentesis.

Alternatively we can refer you to private Fetal Medicine Consultant (consultation cost is not included in our service).

We will also offer Early Fetal Echocardiography for free (regular cost of the examination £300) for all our patients with high chance NIPT for trisomy21 / trisomy18 / trisomy 13.

What are the reasons for Harmony Test false positive results?

Although the Harmony Test is very accurate, around 20% (1 in 5) of positive high chance for Downs syndrome results are false and the baby does not in fact have Down’s syndrome.

Biological factors with the potential to cause discordance between cfDNA results and baby’s genetic status include uncommon conditions like confined placental mosaicism, fetal mosaicism, maternal chromosome changes, and the presence of an unrecognised, nonviable (or viable) twin.

What do NIPT no-call results mean?

Most pregnant women receive complete results from cfDNA testing, indicating either a high or low probability for aneuploidy.

In about 3% of cases (more common with Harmony test) we will need to contact you without giving you a test result and ask to come for additional sample of blood or to give us more information about your pregnancy or medical history. There will be no extra cost for additional blood test.

It is because in small proportion of blood specimens submitted after 10 weeks gestation there is insufficient amount of baby’s cfDNA. This situation called low fetal fraction. The chance to have low fetal fraction is getting higher with increased maternal body weight. There are other rare factors making NITP results inconclusive.

In the case of Harmony Test no-call results we will discuss with you options of alternative screening and/or referral for diagnostic testing if you either decline a second attempt at NIPT or do not receive a result after two attempts.

Our NIPT Refund Policy

The Harmony scan (and Invitae NIPS) can only be done from a gestational age of 10 weeks – TDL/Invitae do not accept any blood samples for patients below that Gestational Age. We recommend to wait until a gestational age of 10 weeks + 2 days to perform the Harmony/Invitae Scan to avoid having to come in more than once.

In case you booked for Initae/ Harmony Scan, but the ultrasound scan indicated a GA below 10 weeks, we will have to rearrange for you to come in at a later date for an additional cost of £50 to cover for our staffing cost.

In case of No-Call results from the test (about 3% of the cases), we will be happy to schedule in another time to draw another blood sample free of charge. In case of a second No-Call result, we will refund the Harmony Test portion of the appointment charge as per below. If, upon discussion with our clinician, you decide that the Harmony Test is not the right decision for you, we will refund the Harmony Test proportion of the appointment and will only charge for the scan.

In the case of inconclusive results for Downs syndrome or trisomies 18 or 13 we are committed to refund your for the Harmony Test cost.

Because the Harmony Test is being undertaken by third party – TDL (The Doctors Laboratory) we will contact them to arrange the refund. The refund will be for Harmony Test only (we can not compensate cost of ultrasound) and will be processed in a few business days.

There is no reimbursement for inconclusive fetal sex results. In those rare cases we will offer you anatomy and gender scan for reduced cost and will discuss the findings and need for further referrals.

Should I delay the NIPT for 12-14 weeks and perform it after my NHS NT Scan?

No, we think it is outdated approach and the best way is to perform both 10 Weeks Anomaly Scan and NIPT at 10-11 weeks. The benefit of this approach is that the tests are performed as early as technically possible.

Understandably it will be impossible to visualise some fetal structures and organs at 10 weeks and some structural anomalies will be undiagnosed at this very early stage. Keeping this in mind, we recommend to perform our Early Fetal Scan at 15-16 weeks for further reassurance and exclusion of majority severe structural anomalies.

Learn more about our Early Pregnancy Scans.

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London Pregnancy Clinic

36 Spital Square

London E1 6DY
United Kingdom

Office Hours

Monday – Friday


Public Transport

Elizabeth, Central, Circle, Hammersmith & City and Metropolitan lines to Liverpool Street or Northern line to Moorgate.

Overground at Shoreditch High Street. All stations within 5-10 minutes' walk.


We are within the Congestion Charge Zone (just!) with a few pay-and-display parking spaces in front of the building. 

Parking available in Shoreditch which is just outside the Congestion Charge Zone.

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