Chromosomes are genetic structures found in nearly every cell of our bodies. The first cell of an embryo is made up of a set of chromosomes from the sperm and another set from the egg. But if the cell doesn’t have the right number of chromosomes -  known as aneuploidy - this can lead to implantation failure, miscarriage or a baby affected with a genetic condition.


Pre-implantation genetic testing for aneuploidy (PGT-A), previously known as PGS testing, is a genetic screening test performed on embryos produced during an IVF treatment cycle. PGT-A gives information about your embryo's genetic health to help us select healthy embryos for transfer to improve your chance of achieving a successful pregnancy. 

Main benefits at a glance


  • Reduced risk of miscarriage
  • Reduced number of IVF cycles needed to achieve pregnancy, potentially reducing the time to pregnancy and the costs of extra cycles
  • More confidence in transferring a single embryo, avoiding health risks associated with twin or triplet pregnancies
  • Freezing and storing embryos that are genetically balanced to improve the success of frozen embryo transfers

Benefits exclusive to CARE patients

  • A clear and straightforward pricing approach
  • Time lapse imaging with CAREmaps is included. This provides a video of embryo development and information which may further enhance outcomes
  • Specially trained doctors to provide you with specialist PGT-A advice

Fee information

Initial fee

This includes CAREmaps, biopsy and set up fee - £1,225

Additional fee per embryo tested - £315

Refund information

Our refund process is simple and transparent too

i) 100% (of the £1225 PGT-A fee), if there are no eggs or fertilisation


ii) a partial refund of the fee if your treatment cycle does not result in usable blastocysts, or if you elect to abandon embryo testing

What does PGT-A involve?

Usually our embryologists choose embryos for transfer based on the way they look and develop. This certainly does work, but PGT-A lets us go deeper, allowing us to analyse the genetic makeup of embryos and check that they have the right number of chromosomes before they’re transferred to the womb.

By using PGT-A our embryologists can single out embryos with abnormalities before transfer. This improves IVF success rates for some patients and reduces the likelihood of miscarriage.

With PGT-A, each embryo will have one of four results


This means the embryo is genetically balanced with 46 chromosomes. These embryos can be transferred.


Aneuploid embryos aren’t genetically balanced and have too few, or too many, chromosomes. We won’t transfer these embryos, as they’re more likely to result in failed treatment or miscarriage.


Mosaic embryos have some cells that are euploid and some that are aneuploid. Depending on the chromosomes affected, we might still be able to transfer these embryos. If you have mosaic embryos we’ll offer you an appointment with a genetics counsellor to discuss your options further.

No result

In less than 5% of cases, we simply won’t be able to tell whether the embryo is euploid or aneuploid. These can still be transferred or, in special circumstances, they might be re-biopsied.

Could PGT-A be right for me?

If you’ve had treatment before that hasn’t worked, you’ve suffered miscarriages, or if you’re a woman in your mid–30s or older, we might recommend PGT-A; it could be that a chromosomal problem is the reason behind your failed treatments. Research suggests that more than 50% of human eggs have chromosomal problems and that this increases with age, so it’s thought to be the main reason older women can struggle to start or grow their families.

During your next cycle, we can use PGT-A to help us choose embryos with the right number of chromosomes for transfer, which could give you a better chance of success.

Patients in their first cycle who have suffered miscarriage previously or who are older than 35 may also wish to consider PGT-A.

Pre-implantation genetic testing has the potential to:

  • PGT-A testing can identify the embryos with the correct number of chromosomes which are more likely to develop into a healthy baby. PGT-A testing can’t change the number of viable embryos available for transfer but, by transferring only those that have the correct number of chromosomes, the time taken to establish a pregnancy can be shorter and the misery of failed cycles and risks of miscarriage can be reduced.
  • Where patients have undergone multiple rounds of IVF and have no explanation for the treatment failure, PGT-A testing can sometimes provide answers and help with decisions about future treatment options.
  • CARE’s own data shows that by performing PGT-A and transferring euploid embryos clinical pregnancy rates (CPR) are increased. In the year to 30 September 2019 CPR per embryo transfer across patients of all ages following PGT-A was 49%[1] compared with 38% in non PGT-A cycles.[2]

[1] Based on 573 single euploid embryo transfers resulting in 281 pregnancies with a foetal heartbeat

[2] Based on 2645 embryo transfers resulting in 1016 pregnancies with a foetal heartbeat

The PGT-A process


Embryos are produced through an IVF cylce

Embryo biopsy

At 5-6 days after fertilisation embryos should reach the blastocyst stage. Blastocysts contain approximately 100 to 200 cells arranged into an inner cell mass and an outer ring of cells called the trophectoderm. The inner cell mass is made up of undifferentiated stem cells that will go on to form the foetus. The trophectoderm is a layer of cells that will become the placenta. A few trophectoderm cells are carefully removed by our embryologists and sent to the genetics laboratory for assessment, while we freeze your embryos and keep them safe.

Embryo freezing

We are very experienced in freezing and thawing of embryos, we use a process called ‘vitrification’. Vitrification involves much more rapid cooling than other less advanced methods of freezing, and it prevents ice crystals from forming. This preserves the quality of the cells and improves the chances of success when they are thawed. Vitrification has greatly improved the success of embryo freezing and it’s now a very reliable practice.


Testing is carried out using cutting-edge technology to analyse the number of chromosomes present within the embryo's cells.

Embryo transfer

Embryos which are identified as having the correct numbers of chromosomes and therefore most likely to result in a healthy baby are selected for transfer, or we can freeze your embryos for future use.
HFEA Comment

Are there any risks associated with PGT-A?

There is a possible but unquantified risk that removing cells from an embryo may damage it and prevent it from developing. However, the first births following embryo biopsy for genetic screening were reported in 1990 and since then, thousands of children have been born, and health risks following embryo biopsy have not been identified as different from IVF/ICSI pregnancies in general.

The necessary freezing and thawing of embryos is highly successful with over 95% survival rate after thawing. There is however, a small risk that the embryo will not survive the process.

What is the evidence for PGT-A?

The independent regulator of fertility treatment, the Human Fertilisation and Embryology Authority (HFEA), has developed a ‘red-amber-green’ rating system and provides information on their website about treatments that are offered on top of your routine fertility treatment – known as treatment add-ons. They consider that the only way to be confident that a treatment is effective enough to be used routinely is to carry out a randomised controlled trial (RCT). In an RCT, patients are assigned randomly to two groups: a treatment group, given the new treatment and a control group, given a well-tried treatment or a placebo.

The HFEA has given PGT-A a red rating because it considers that there is no evidence from such trials that PGT-A increases the overall chances of having a baby. There is information on the HFEA website about PGT-A that you may find useful to consider.

CARE did participate in a large scale RCT called the STAR trial, which was published in December 2019. This trial concluded that there was a significant increase in pregnancy rate in a subset of women aged 35–40 where they had more than two embryos available for testing, although overall in all age groups there was no increase in ongoing pregnancy. However, we recognise that that more robust clinical and laboratory trials are needed to prove whether or not PGT-A significantly increases live birth rates. 

It is important to understand that PGT-A will not increase your overall chances of having a baby, although it may shorten your time to pregnancy by helping us select the best embryo sooner. For more information, please speak to your clinic team who will give you detailed patient information documents which outline all the relevant points about PGT-A, or you can visit the HFEA website. We also have some FAQs which you  might find helpful read our FAQs.