At a glance
An explainer on PGT-A, PGT-M and PGT-SR for international patients over 40 considering IVF in Thailand, covering age-related aneuploidy, test limitations and questions to ask a clinic.
If you are over 40 and considering IVF in Thailand, you may have read that preimplantation genetic testing (PGT) can help select embryos. PGT is a group of laboratory tests performed on a small number of cells taken from an embryo during IVF. It does not treat infertility, improve egg quality or guarantee a pregnancy. Instead, it provides information about the chromosomal or genetic makeup of an embryo, which you and your clinician can use when deciding which embryo(s) to transfer. This guide explains the main types of PGT, why age is relevant, and what the results can and cannot tell you.
At a glance
- PGT-A looks at the number of chromosomes in an embryo; the chance of chromosomal errors rises with maternal age.
- PGT-M looks for a specific inherited condition known to run in a family.
- PGT-SR looks at chromosome rearrangements, such as translocations, that a parent may carry.
- PGT is not a guarantee of pregnancy, live birth or a healthy child.
- Whether PGT is appropriate for you depends on your history, your age, the reason for testing and clinic guidance.
What PGT means in plain language
During IVF, eggs are fertilised in the laboratory and embryos begin to develop. If PGT is planned, an embryologist removes a few cells from an embryo at a specific stage, usually the blastocyst stage. Those cells are tested, and the embryo is typically frozen while results are awaited. A later transfer cycle uses an embryo selected partly on the basis of the test result.
PGT is not one single test. It is an umbrella term for several different investigations, each with a different purpose. The type your clinic discusses with you should match the question you are trying to answer.
The three main types of PGT
| Test | What it looks at | Typical reason it is discussed |
|---|---|---|
| PGT-A | Number of chromosomes in an embryo (aneuploidy screening) | Age-related risk of chromosomal errors, or a history of repeated implantation failure or miscarriage |
| PGT-M | A specific gene variant or inherited condition | A known familial genetic condition, such as cystic fibrosis or Huntington’s disease |
| PGT-SR | Structural chromosome rearrangements | A parent carries a translocation or similar rearrangement |
Some clinics may also discuss other forms of testing. The names and availability of specific tests can vary, so ask your clinic to explain exactly which test is being proposed and why.
Why age matters: aneuploidy and egg quality
Human eggs are formed before birth and mature over decades. As a woman ages, the chance that an egg will have an incorrect number of chromosomes increases. An embryo with an incorrect number of chromosomes is described as aneuploid. Many aneuploid embryos do not implant, and some pregnancies involving aneuploid embryos end in miscarriage. A small number can result in a live birth with a chromosomal condition, such as Down syndrome.
This age-related tendency is sometimes described as a decline in egg quality, but it is more accurate to think of it as a change in the proportion of eggs with chromosomal errors. It is not something you can feel, and it does not mean every egg or every embryo will be affected. PGT-A is one way to gather information about the chromosomal status of the embryos you have, but it does not change the underlying biology of the eggs or embryos.
What PGT-A can and cannot tell you
PGT-A is designed to detect whole-chromosome gains or losses. It can identify embryos that are likely to be euploid (the expected number of chromosomes) or aneuploid. It cannot tell you whether an embryo will implant, whether a pregnancy will continue, or what a child’s health, development or appearance will be.
PGT-A also has technical limitations. It is a screening test, not a diagnostic test, and it can produce results that are inconclusive, borderline or affected by mosaicism (where an embryo has a mix of cells with different chromosome numbers). Some embryos may be reported as mosaic, and the implications of transferring a mosaic embryo are not fully understood. Your clinic should explain what a particular result means for your specific situation.
PGT-M and PGT-SR: when the question is different
PGT-M is used when there is a known inherited condition in the family. It looks for a specific gene variant that the parents may pass on. PGT-SR is used when a parent carries a chromosome rearrangement, such as a translocation, which can increase the risk of miscarriage or a child with a chromosomal condition. These tests are not about age-related aneuploidy; they answer a different question. If you have a family history of a genetic condition or a known rearrangement, ask your clinic whether PGT-M or PGT-SR is relevant for you.
Is PGT right for you? Questions to consider
PGT is not a required step in IVF, and it is not suitable for everyone. Whether it is offered or recommended depends on your medical history, your age, the reason for testing, the number of embryos available, and clinic policy. Some people choose PGT to gain information; others decide against it because of cost, the possibility of no transferable embryos, or the wish to avoid embryo freezing and testing.
There is no single correct choice. A useful next step is to ask your clinic the following questions:
- Which type of PGT are you recommending for me, and why?
- What will the result tell us, and what will it not tell us?
- What happens if the result is inconclusive or mosaic?
- How many embryos would need to be tested for the test to be useful in my case?
- What are the alternatives to PGT, and what are the trade-offs?
- What are the costs, including any separate laboratory, freezing and storage fees?
- What are the clinic’s policies on embryo storage, disposal and transport?
Practical planning for international patients
If you are travelling to Thailand for IVF with PGT, planning involves more than the test itself. You will need to consider how long you can stay, how many visits are required, and how results will be communicated to you. Because PGT often involves freezing embryos and transferring them in a later cycle, your timeline may extend over more than one trip or require coordination with a clinic in your home country.
Before you commit, ask your clinic to explain:
- How many days you need to be in Thailand for monitoring, egg collection and any transfer.
- How results are shared and how follow-up is arranged if you return home.
- What documents or records the clinic needs from you, and whether translations are required.
- What payment, cancellation and refund policies apply.
- Whether the clinic can support you if you need to pause or change plans.
Legal and regulatory requirements can change and may differ depending on your situation. Always confirm current requirements with the clinic and, where relevant, with the appropriate authority. You can also read more general information on our PGT in Thailand page and browse our guides for related topics.
Alternatives and limitations
PGT is one option among several. Some people proceed with IVF without PGT, accepting that embryo selection will be based on development and appearance rather than genetic testing. Others may consider donor eggs, adoption or choosing not to pursue further treatment. These are personal decisions, and no single path is right for everyone.
It is also important to recognise that PGT cannot create embryos, improve egg or sperm quality, or overcome all causes of infertility. It does not replace prenatal testing, which may still be offered during pregnancy. And it does not remove the uncertainty that is part of any fertility treatment.
Next steps
If you are over 40 and considering PGT in Thailand, start by clarifying your own questions. Write down what you hope to learn from testing and what you would do with the information. Then discuss those points with a qualified fertility clinician who can review your history and explain whether PGT is likely to be useful in your case. For general background, see our FAQ section.
Frequently asked questions
Does PGT-A improve my chances of having a baby if I am over 40?
PGT-A can provide information about the chromosomal status of an embryo, but it does not guarantee a pregnancy or a live birth. It does not change the underlying biology of your eggs or embryos. Whether it improves your individual chances depends on many factors, and your clinic can discuss what is known and what remains uncertain in your situation.
What is the difference between PGT-A, PGT-M and PGT-SR?
PGT-A screens for an incorrect number of chromosomes in an embryo, which becomes more common with age. PGT-M looks for a specific inherited condition known to run in a family. PGT-SR looks for chromosome rearrangements, such as translocations, that a parent may carry. Each test answers a different question.
Can PGT tell me if my embryo is healthy?
No. PGT-A looks at chromosome number, and PGT-M and PGT-SR look at specific genetic issues. None of these tests can confirm that an embryo is completely healthy or predict a child's future health, development or appearance. PGT is a screening or diagnostic tool with limitations, and results should be interpreted with your clinician.
What happens if my PGT result is inconclusive or mosaic?
Some embryos may be reported as inconclusive or mosaic, meaning the result is not clear-cut. The implications of transferring such an embryo are not fully understood, and practices vary. Your clinic should explain what a specific result means for you and what options are available.
Is PGT required for IVF in Thailand?
No. PGT is not a required part of IVF, and it is not suitable for everyone. Whether it is offered or recommended depends on your medical history, your age, the reason for testing, the number of embryos available, and clinic policy. You can discuss the pros and cons with your fertility clinician.
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Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.
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