PGT-A vs PGT-M in Thailand: How to Choose the Right Genetic Test for IVF

PGT-A vs PGT-M: A Quick Orientation

If you are planning IVF in Thailand and have been offered preimplantation genetic testing, you may be weighing two common options: PGT-A and PGT-M. Both tests are performed on embryos created through IVF, but they answer different questions. PGT-A screens embryos for an abnormal number of chromosomes (aneuploidy), which is more common with advanced maternal age. PGT-M looks for a specific single-gene disorder that one or both parents are known to carry. Your choice depends on your medical history, your reason for testing, and what you hope to learn before embryo transfer.

This guide explains the purpose, process, and practical considerations of each test, and helps you frame the right questions for your fertility clinic in Thailand.

At a Glance: Key Differences

• PGT-A checks for chromosomal abnormalities (too many or too few chromosomes). It is often recommended for women of advanced maternal age, repeated implantation failure, or recurrent miscarriage.
• PGT-M tests for a specific inherited genetic condition, such as cystic fibrosis or thalassemia, when both partners are known carriers or have a family history.
• PGT-SR (not the focus here) screens for structural rearrangements like translocations, which can affect chromosome pairing.
• Both tests require IVF, embryo biopsy, and genetic analysis. The process and timeline are similar, but the laboratory techniques differ.

What Is PGT-A?

PGT-A (preimplantation genetic testing for aneuploidy) is a screening test. It counts the number of chromosomes in each embryo. Humans typically have 46 chromosomes (23 pairs). An embryo with an abnormal number—such as an extra chromosome 21 (Down syndrome) or a missing chromosome—is considered aneuploid. Most aneuploid embryos fail to implant or miscarry, and some can lead to a live birth with a chromosomal condition.

PGT-A is often offered to patients who are at higher risk of producing aneuploid embryos, including women over 35, those with a history of recurrent pregnancy loss, or repeated failed IVF cycles. It can also be used to select a single embryo for transfer, reducing the chance of multiple pregnancy.

It is important to note that PGT-A does not guarantee a healthy baby. It only screens for common chromosomal abnormalities; it does not detect all genetic disorders, and it cannot identify every cause of miscarriage or implantation failure.

What Is PGT-M?

PGT-M (preimplantation genetic testing for monogenic disorders) is a diagnostic test for a specific single-gene disease. It is used when one or both partners are known carriers of a genetic condition, such as cystic fibrosis, sickle cell anemia, Tay-Sachs disease, or thalassemia. The test identifies embryos that carry the disease-causing mutation, allowing the transfer of embryos that are unaffected.

PGT-M requires prior knowledge of the exact genetic mutation in the family. This is usually established through carrier screening or genetic testing of an affected family member. The test is highly specific: it looks for that particular mutation, not for other genetic issues.

PGT-M is not a general health screen. It does not assess chromosome number (that would be PGT-A) and it does not detect all possible genetic conditions. It is a targeted test for a known risk.

How Are the Tests Performed?

Both PGT-A and PGT-M follow a similar IVF pathway:

1. Ovarian stimulation and egg retrieval – You undergo standard IVF to produce embryos.
2. Embryo culture – Embryos are grown in the laboratory for about five to six days, until they reach the blastocyst stage.
3. Biopsy – A few cells are removed from the outer layer of the embryo (trophectoderm), which will become the placenta. The embryo itself is not harmed.
4. Genetic analysis – The biopsied cells are sent to a genetics laboratory. For PGT-A, the chromosomes are counted. For PGT-M, the specific gene is analyzed.
5. Freezing and transfer – While waiting for results, embryos are frozen. Once results are available, a healthy embryo (if any) is selected for transfer in a later cycle.

The biopsy and freezing process is similar for both tests. The main difference is the type of genetic analysis performed. Some clinics may offer combined testing (PGT-A plus PGT-M) if you have both chromosomal and single-gene concerns, but this is not always necessary.

Which Test Is Right for You?

Your choice depends on your medical history and the reason for testing. Here are some general scenarios:

• Advanced maternal age (typically over 35) – PGT-A may be offered to screen for chromosomal abnormalities, as the risk of aneuploidy increases with age.
• Known carrier of a single-gene disorder – PGT-M is the appropriate test to avoid passing on that specific condition.
• Both partners are carriers of the same autosomal recessive condition – PGT-M is strongly indicated.
• History of recurrent miscarriage or implantation failure – PGT-A may be considered to rule out chromosomal causes, but it is not a guarantee of success.
• Family history of a chromosomal structural rearrangement – PGT-SR (not covered in detail here) may be recommended.

It is possible to have both PGT-A and PGT-M in the same cycle if you have both indications. Your fertility specialist and genetic counselor can help you decide based on your specific situation.

Cost and Time Considerations

The cost of PGT-A and PGT-M varies widely between clinics in Thailand and depends on the number of embryos tested, the laboratory used, and whether you combine tests. PGT-M is generally more expensive than PGT-A because it requires developing a customized test for your specific mutation, which involves additional laboratory work and sometimes a prior “work-up” using a blood sample from you and your partner.

Time is also a factor. PGT-A results typically take about a week, while PGT-M may take longer, especially if a custom test needs to be developed. This can affect your IVF cycle timeline, as embryos are frozen while you wait.

Because costs and timelines are not standardized, it is essential to ask your clinic for a detailed breakdown before you commit. Confirm what is included in the quoted price, such as biopsy, genetic analysis, freezing, and any additional consultations.

Limitations and Risks

No genetic test is perfect. Both PGT-A and PGT-M have limitations:

• Mosaicism – Embryos may have a mix of normal and abnormal cells. PGT-A may not always detect this, and the clinical significance is still being studied.
• False results – There is a small risk of a false positive or false negative, though modern techniques are highly accurate.
• Embryo damage – Biopsy carries a small risk of damaging the embryo, though this is rare in experienced hands.
• Not a guarantee – A “normal” embryo may still fail to implant or miscarry for other reasons. PGT does not guarantee a live birth.

It is also important to understand that PGT-A does not screen for all genetic disorders, and PGT-M only looks for the specific mutation you are testing for. Neither test can predict the health of a future child beyond the tested conditions.

Questions to Ask Your Clinic in Thailand

Before deciding, ask your fertility clinic these questions:

• What is your experience with PGT-A and PGT-M? How many cycles have you performed?
• Which genetics laboratory do you use, and what is their accreditation?
• What is the exact cost for PGT-A and PGT-M, including biopsy, analysis, and freezing?
• How long will it take to get results, and how does that affect my treatment timeline?
• Do you offer genetic counseling to help interpret results?
• What are the success rates for embryo transfer after PGT in your clinic? (Ask for their own data, not general statistics.)
• What happens if no embryos are suitable for transfer?

Next Steps

If you are considering PGT-A or PGT-M in Thailand, start by gathering your medical records, including any genetic test results or family history. Then, schedule a consultation with a fertility specialist who can review your case and recommend the most appropriate testing strategy. You may also want to speak with a genetic counselor to understand the implications of your results.

Remember, the choice between PGT-A and PGT-M is not about which test is “better” overall, but which test addresses your specific medical needs. Take your time, ask questions, and make an informed decision with your healthcare team.

For more general information about PGT in Thailand, see our PGT in Thailand guide. You can also explore our other guides and check the FAQ section for common questions.

Frequently asked questions

Can I have both PGT-A and PGT-M in the same IVF cycle?

Yes, it is possible to combine PGT-A and PGT-M in the same cycle. This is done when you have both chromosomal and single-gene concerns. The biopsy process is the same, but the genetic analysis will include both chromosome counting and specific gene testing. This may increase the cost and time for results, so discuss the details with your clinic.

Is PGT-A necessary for all IVF patients?

No, PGT-A is not necessary for everyone. It is typically recommended for patients with advanced maternal age, a history of recurrent miscarriage, or repeated implantation failure. For younger patients with no known genetic issues, PGT-A may not be needed. Your doctor will advise based on your individual circumstances.

How accurate are PGT-A and PGT-M?

Both tests are highly accurate, but they are not infallible. PGT-A has a small risk of false results due to mosaicism or technical errors. PGT-M is very accurate for the specific mutation tested, but it does not detect other genetic conditions. Discuss the accuracy and limitations with your clinic and genetic counselor.

Does PGT guarantee a healthy baby?

No, PGT does not guarantee a healthy baby. It reduces the risk of transferring embryos with certain chromosomal abnormalities or specific genetic disorders, but it cannot prevent all birth defects or health issues. Many factors affect pregnancy outcome, including embryo quality, uterine environment, and overall health.

What is the difference between PGT-A and PGT-SR?

PGT-A screens for an abnormal number of chromosomes (aneuploidy), while PGT-SR is used when one parent has a structural rearrangement of chromosomes, such as a translocation. PGT-SR identifies embryos with unbalanced chromosome arrangements that could lead to miscarriage or birth defects. It is a different test with a different purpose.

Continue your research

• PGT in Thailand overview
• PGT and IVF guides
• Frequently asked questions

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.