At a glance
PGT-A and PGT-M answer different questions. This guide explains the purpose, sample, typical indications and reporting of each test so you can discuss the right option with your clinic.
PGT-A and PGT-M are both preimplantation genetic tests, but they answer different questions. PGT-A looks at the number of chromosomes in an embryo, while PGT-M looks for a specific inherited condition that runs in a family. Neither test is a guarantee of pregnancy or a healthy child, and neither is automatically right for every patient. The choice depends on your clinical history, your genetic context and what your treating clinic can offer. This guide explains how the two tests differ so you can ask clearer questions during your research.
At a glance
- PGT-A checks chromosome number (for example, whether there is an extra or missing chromosome).
- PGT-M checks for a known gene change linked to a specific inherited condition.
- PGT-SR is a related test for structural chromosome rearrangements.
- Sample, timing and reporting differ between tests.
- Test choice follows clinical and genetic context, not a ranking of better or worse.
- Results are reported as risk information, not as a diagnosis of an embryo or a guarantee of outcome.
What PGT-A and PGT-M are designed to do
Preimplantation genetic testing (PGT) is a group of laboratory tests performed on embryos created through IVF. Each type of PGT has a different purpose.
PGT-A (aneuploidy) is designed to screen for an abnormal number of chromosomes. Chromosomes are the structures that carry genetic material. A typical embryo has a specific number of chromosomes, and PGT-A looks for extra or missing chromosomes. This kind of chromosome difference can occur in any pregnancy and becomes more common with age, but it is not the same as a specific inherited disease.
PGT-M (monogenic) is designed to look for a specific gene change that is known to run in a family. It is usually considered when there is a known inherited condition, such as cystic fibrosis, spinal muscular atrophy, thalassaemia or another single-gene disorder. PGT-M is not a general screen; it is targeted at a condition that has already been identified in the family or in the parents.
PGT-SR (structural rearrangement) is a related test for families where a parent carries a balanced chromosome rearrangement, such as a translocation. It is sometimes grouped with PGT-A and PGT-M in patient information, but it addresses a different situation.
How the tests differ: purpose, sample, indications and reporting
The table below compares PGT-A and PGT-M across the categories that international patients most often ask about. It is a general orientation, not a clinical recommendation.
| Category | PGT-A | PGT-M |
|---|---|---|
| Main purpose | Screen for abnormal chromosome number | Look for a specific inherited gene change |
| What it looks at | Number of chromosomes | A known gene or gene region linked to a family condition |
| Typical situation | No known inherited condition; may be discussed based on age, history or prior IVF outcomes | Known inherited condition in the family or in one or both parents |
| Sample | Cells taken from the embryo during IVF | Cells taken from the embryo during IVF, plus a DNA sample from the parents or family for test design |
| Timing | After embryo development reaches a certain stage; timing is set by the clinic | After embryo development reaches a certain stage; test design may need to be prepared before the IVF cycle |
| Reporting | Result describes chromosome number findings for the tested embryo | Result describes whether the specific gene change was found, not found, or could not be clearly determined |
| Limitations | Does not test for all genetic conditions; may not give a clear result in every case | Only tests for the condition it was designed for; may not give a clear result in every case |
Both tests are performed on a small sample of cells removed from an embryo. This is called an embryo biopsy. The exact laboratory process, the number of cells taken and the timing of the biopsy are determined by the treating clinic and its laboratory. You should ask your clinic to explain its own protocol.
Why the choice is not a ranking
PGT-A and PGT-M are not competing options where one is better than the other. They answer different questions. A patient with a known inherited condition may be offered PGT-M, while a patient without a known inherited condition may discuss PGT-A. Some patients may be offered both, depending on their situation. The decision is clinical and genetic, and it should be made with your treating team.
It is also important to understand that PGT is not a guarantee. A test result can reduce uncertainty about a specific question, but it cannot guarantee a pregnancy, a live birth or a child without any health condition. PGT does not replace other prenatal testing or clinical care.
Questions to ask your clinic about PGT-A and PGT-M
When you contact a clinic in Thailand or elsewhere, these questions can help you compare what is actually offered and how it fits your situation.
- Which PGT tests does your clinic and laboratory offer?
- For my situation, what information would PGT-A or PGT-M provide, and what would it not provide?
- What are the limitations and possible unclear results for each test?
- What sample is needed from me or my family, and when does it need to be provided?
- How and when will results be reported, and who will explain them to me?
- What are the alternatives if I choose not to do PGT, or if PGT is not suitable for my situation?
- What costs are involved, and what do they cover? (Ask for a written breakdown.)
- What are the legal and regulatory requirements for international patients in your location?
How to prepare for a PGT conversation
Preparation can make your consultation more productive. Consider the following steps:
- Gather your personal and family medical history, including any known genetic conditions.
- Collect any previous genetic test results or reports you have.
- Write down your main questions and concerns before the appointment.
- Ask whether a genetic counsellor is available, and whether an interpreter is needed.
- Confirm the clinic’s process for international patients, including how records are shared and how follow-up is arranged.
- Ask for a written summary of any recommended tests, including their purpose and limitations.
For more general information about PGT in Thailand, see our PGT in Thailand page. If you are planning your first contact with a clinic, our international patients page outlines common steps. You can also browse our guides for related topics, and check the FAQ for answers to frequent questions.
What PGT does not tell you
PGT-A and PGT-M have limits. PGT-A does not detect every possible genetic condition, and it does not test for single-gene disorders unless a specific test is designed. PGT-M only tests for the condition it was designed for; it does not screen for other conditions. Both tests can sometimes produce a result that is not clear, and in those cases the clinic may discuss what the result means for that embryo. Neither test can guarantee that an embryo will implant, that a pregnancy will continue, or that a child will be free of all health conditions.
Because of these limits, PGT is usually one part of a broader IVF plan. Your clinic may also discuss other factors such as embryo development, uterine factors and your overall health. The decision to use PGT, and which type, should be based on your individual clinical and genetic context.
Next steps for international patients
If you are researching PGT-A and PGT-M from outside Thailand, a practical next step is to contact a clinic that treats international patients and ask for a consultation. Prepare your questions, ask for written information, and confirm any legal, travel or documentation requirements directly with the clinic or the relevant authority. Because requirements can change, always verify current details before making plans.
This article is for general education and does not replace advice from your treating clinician or a genetic counsellor. Test selection should be individualised.
Frequently asked questions
Can PGT-A and PGT-M be done at the same time?
In some situations, a clinic may discuss using both tests together, but this depends on the laboratory's capabilities and your clinical and genetic context. Ask your treating clinic whether combined testing is possible for your case and what the limitations would be.
Does PGT-A test for inherited diseases like thalassaemia?
PGT-A looks at chromosome number, not at specific gene changes. Conditions like thalassaemia are usually investigated with PGT-M, which is designed for a known gene change. If you have a family history of a specific condition, tell your clinic so they can advise on the appropriate test.
Is PGT-M only for couples where both partners are carriers?
PGT-M may be considered when there is a known inherited condition in the family, which can include situations where one or both parents carry a gene change. The decision depends on the specific condition and your genetic evaluation. A genetic counsellor or your treating clinician can explain whether PGT-M is relevant for you.
What does an unclear PGT result mean?
Sometimes a PGT result does not give a clear answer about the embryo. This can happen for technical reasons. Your clinic will explain what an unclear result means for that embryo and what options you have. It does not automatically mean the embryo is affected or unaffected.
Does PGT guarantee a healthy baby?
No. PGT can provide information about specific chromosome or gene questions, but it cannot guarantee a pregnancy, a live birth or a child without any health condition. It is one part of IVF care, and other factors also affect outcomes.
Continue your research
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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