Understanding how PGT-A affects IVF outcomes

Fertility treatment can be both emotionally and physically demanding, and it’s natural to have questions along the way. 

At Bourn Hall, our goal is to ensure you feel supported and informed throughout your journey. Many patients choose standard in vitro fertilisation (IVF) treatment, while others explore adding preimplantation genetic testing for aneuploidy (PGT-A) – a genetic test that provides extra insight into the health of embryos before transfer.

In this article, we explain what PGT-A involves, why some patients opt for it and how it may influence IVF outcomes. Our aim is to provide balanced and evidence-based information so you can make confident decisions that feel right for you and your family.

What is PGT-A and how does it work?

PGT-A is a type of genetic test that can be used during an IVF cycle to check whether an embryo has the correct number of chromosomes (the genetic instructions that guide healthy embryo development).

During IVF, eggs are collected and fertilised in the laboratory. The embryos are then grown for around five to six days until they reach a stage called a blastocyst. At this point, the embryology team can safely remove a tiny sample of cells from the outer layer of the embryo. All the sampled embryos are frozen, and we wait for the results. There is no evidence that this procedure harms the embryo or affects its continued growth.

The sample is tested to see whether the embryo has the correct number of chromosomes. Embryos with the right number are generally more likely to develop normally, while those with more or fewer chromosomes are very unlikely to become babies.

It’s important to remember that PGT-A does not offer a guarantee of pregnancy. What it does provide is valuable information about each embryo, helping you and your fertility team make informed decisions about which embryo to transfer first.

Why might I consider PGT-A alongside IVF?

There are several reasons why you might consider adding PGT-A to your IVF treatment. For many people, it’s simply about gaining clearer information and feeling more confident about the next step of their IVF journey.

Some patients explore PGT-A after experiencing multiple miscarriages or IVF cycles that haven’t worked as hoped. In these situations, it can be reassuring to understand whether chromosome differences in embryos may have played a role.

Age can also be a factor. As women get older, it becomes more common for embryos to have chromosome flaws. PGT-A can help identify which embryos are more likely to develop successfully.

PGT-A may also be considered when there are several embryos to choose from. By providing more information about each embryo, it can help guide which one to transfer first and may reduce the number of transfers needed. Focusing on the embryos with potential helps to reduce the number of failed transfers, which we know can be emotionally challenging.

PGT-A also helps to maintain a single embryo transfer approach during the fertility journey. Without PGT-A, women in their late thirties or early forties would normally transfer two embryos together, in order to compensate for the lower potential of their untested embryos related to their age. Transferring two embryos together accounts for the overwhelming majority of twins after IVF, which is well recognised as high-risk pregnancies and the most profound risk stemming from fertility treatment.

However, PGT-A allows focus only on high-potential embryos, thereby reducing the pressure of transferring more than one embryo at a time. This is a safe and effective way of doing IVF for many women.

Finally, PGT-A allows family-building options in a more controlled way than conventional IVF. Take the scenario of a 36-year-old woman who has conventional IVF and is successful in having a baby. By the time she has the baby – and perhaps allowing for breastfeeding and other life adjustments – she will likely come back for another baby after a couple of years at least. If she is not fortunate to have frozen embryos already in storage, or if these frozen embryos are not successful, she will need to consider a new egg harvest process at an age where there is diminished return for her efforts.

If, on the other hand, she has stored a reasonable number of PGT-A screened, normal embryos before getting pregnant in the first place, she can be confident that she will have good chances of another baby via these embryos, without undergoing further egg harvests and without the pressure of time.

At Bourn Hall, the decision to use PGT-A is always personal. Your specialist will take the time to understand your history, goals and treatment plans, and discuss whether PGT-A could offer helpful insight for your individual situation.

How PGT-A may influence IVF outcomes

PGT-A can play a role in shaping your IVF journey, though its impact can vary from person to person. One of the main ways it may help is by providing a clearer picture of which embryos are most likely to develop normally. This information can make it easier to select the embryo with the best chance of successful implantation.

For some patients, PGT-A may also reduce the risk of miscarriage, which increases with age. Women in their forties may have almost 1 in 2 chances of experiencing a miscarriage. Many early miscarriages happen because an embryo has an unexpected number of chromosomes. By identifying embryos that are more likely to grow as expected, PGT-A can sometimes help lower this risk. The risk of miscarriage is not eliminated, but PGT-A can reduce the risk of miscarriage substantially, particularly for older women. In practice, it may bring the risk of miscarriage down to 10% or less, which is low compared even to younger women.

Another possible benefit is that patients may achieve a pregnancy in fewer transfers. Choosing an embryo with a higher likelihood of success can shorten the time it takes to reach a positive outcome. This is a major benefit, as every failed transfer or miscarriage often comes with a heavy emotional burden.

Although these possibilities can be encouraging, it’s important to remember that outcomes are not guaranteed, and PGT-A isn’t the right choice for everyone. Your specialist will always help you understand what the potential benefits mean for your own situation.

Does PGT-A improve IVF success rates?

The evidence on PGT-A and IVF success rates is mixed, which is why it’s offered selectively rather than as a routine part of treatment.

PGT-A may offer helpful insight for some patients, particularly those with a history of miscarriage, as it can help identify embryos with chromosome differences. 

The Human Fertilisation & Embryology Authority (HFEA) also advises that findings from high-quality evidence suggest PGT-A may reduce the risk of miscarriage for most fertility patients.

However, it does not necessarily increase the overall chance of having a baby. PGT-A offers helpful information, but it does not routinely create more embryos, and some embryos may not be used after testing. For this reason, PGT-A cannot be said to improve the overall chances of having a baby. Its main strength lies in targeting a few selected embryos of higher potential.

Because of these factors, PGT-A is considered an optional IVF add-on. It may be useful for some people, but it is not necessary or suitable for everyone. At Bourn Hall, your specialist will guide you through the evidence with care, tailoring discussions to your medical history, age and treatment goals. 

Understanding the limitations of PGT-A

PGT-A can offer helpful insight, but it’s not the right choice for everyone. Even if an embryo has the expected number of chromosomes, many other factors influence whether it will implant and grow, so the test can’t guarantee a pregnancy.

It’s also possible that PGT-A may reduce the number of embryos available for transfer. Embryos with uniform chromosome flaws are unlikely to be used, which can feel disappointing, especially if only a few embryos were created. Your specialist will guide you through what this might mean for your individual situation and help you weigh up your options.

Because of these considerations, PGT-A is recommended only when it’s likely to add meaningful value to your treatment.

Who might benefit most from PGT-A during IVF treatment?

PGT-A is not necessary for everyone, but there are situations where it may offer extra clarity or support.

It may be particularly helpful for patients who:

• Are in their late thirties or forties and want additional insight into their embryos
• Have experienced more than one miscarriage and would like to understand whether genetics may have played a role
• Have had IVF cycles that haven’t worked and are looking for more information before trying again
• Have several embryos and would like guidance in choosing which one to transfer first
• Want to potentially reduce the number of transfers they may need
• Need to avoid multiple pregnancy for health reasons
• Experience substantial psychological burden or trauma from a failed transfer or a miscarriage.

Because everyone’s fertility journey is unique, we’ll take the time to review your history, your embryos and your hopes for treatment – exploring whether PGT-A could be a helpful option for you, together.

Explore IVF and PGT-A with Bourn Hall

If you’re considering IVF and wondering whether PGT-A may be helpful, our team is here to guide you. During your consultation, we’ll review your fertility history, explain how PGT-A fits into treatment and help you understand what it could offer in your situation.

Our aim is to provide clear, reassuring information so you can make decisions that feel right for you. Whether you choose standard IVF or IVF with PGT-A, you’ll receive personalised care from a team committed to supporting you at every step.

If you’d like to explore your options or book an appointment, simply get in touch. We’re here to help you move forward with confidence and peace of mind.