At a glance
PGT-A results can feel overwhelming. This guide explains euploid, aneuploid, and mosaic results in plain English and helps you prepare for a conversation with your genetic counselor.
If you have just received your PGT-A results, you may be looking at a report full of unfamiliar terms like euploid, aneuploid, and mosaic. It is normal to feel both hopeful and uncertain. This guide explains the main result categories in plain English and helps you prepare for a detailed discussion with your genetic counselor or fertility specialist.
At a glance: PGT-A result categories
- Euploid – the embryo has the expected number of chromosomes.
- Aneuploid – the embryo has missing or extra chromosomes.
- Mosaic – the embryo has a mix of cells with different chromosome numbers.
- No result – the test did not produce enough information to classify the embryo.
Each category provides different information, and none is a guarantee of pregnancy or a healthy baby. Your clinical team will interpret the result in the context of your medical history and treatment plan.
What is PGT-A?
Preimplantation genetic testing for aneuploidy (PGT-A) is a test that checks embryos for the correct number of chromosomes. Humans typically have 46 chromosomes, arranged in 23 pairs. An embryo with the right number is called euploid. An embryo with missing or extra chromosomes is called aneuploid.
PGT-A is performed on a small number of cells taken from a blastocyst (a day-5 or day-6 embryo) before a potential transfer. The test is not a guarantee of a successful pregnancy or a healthy baby. It is one piece of information that can help you and your clinic decide which embryo to transfer.
Understanding your PGT-A report
Your report will likely list each embryo that was tested and a result for each. The terms may vary slightly between laboratories, but the main categories are described below.
Euploid (normal)
A euploid embryo has the expected number of chromosomes. This is often described as a “normal” result. Euploid embryos have the highest chance of implanting and developing, but they are not a guarantee of pregnancy or a healthy baby. Other factors, such as embryo quality and the health of the uterus, also matter.
Aneuploid (abnormal)
An aneuploid embryo has missing or extra chromosomes. For example, an embryo with an extra copy of chromosome 21 has trisomy 21, which causes Down syndrome. Most aneuploid embryos do not implant or result in a miscarriage. Aneuploid embryos are generally not recommended for transfer, but your clinic will discuss your specific situation.
Mosaic
A mosaic embryo has a mixture of cells: some with the expected number of chromosomes and some with an abnormal number. The report may show a percentage, such as “20% mosaic.” Mosaic results are more complex to interpret. Some mosaic embryos may develop normally, while others may not. The clinical significance depends on the specific chromosomes involved and the percentage of abnormal cells. Your genetic counselor can explain what a mosaic result means for your particular embryo.
No result
Sometimes the test does not produce enough information to classify an embryo. This can happen if the biopsy sample was too small or the DNA did not amplify well. A “no result” does not mean the embryo is abnormal. You may choose to retest, or you may decide to transfer the embryo without further testing, depending on your clinic’s advice.
What your PGT-A result does not tell you
PGT-A only screens for chromosomal abnormalities. It does not test for every genetic condition, and it does not guarantee a healthy baby. Other factors, such as the embryo’s structure, the uterine environment, and your overall health, also affect the outcome. PGT-A is not a substitute for prenatal testing, which can provide additional information during pregnancy.
How to discuss your results with your clinic
Your genetic counselor or fertility specialist is the best person to interpret your results in the context of your medical history. Before your appointment, write down any questions you have. Here are some questions you might ask:
- What does this result mean for the chance of implantation and live birth?
- Are there any additional tests we should consider?
- If the embryo is mosaic, what is the specific risk and what are our options?
- How does my age and medical history affect the interpretation?
- What are the next steps in our treatment plan?
Next steps after receiving your results
After you receive your PGT-A results, you and your clinic will decide which embryo, if any, to transfer. This decision may involve a frozen embryo transfer (FET) cycle. Your clinic will guide you through the process, including any necessary preparation and timing.
If you have questions about PGT-A in general, you can explore our PGT in Thailand page. For more educational articles, visit our guides section. You may also find answers in our FAQ.
Key takeaways
- PGT-A results are not a guarantee of pregnancy or a healthy baby.
- Euploid means the embryo has the expected number of chromosomes.
- Aneuploid means the embryo has missing or extra chromosomes.
- Mosaic means the embryo has a mix of cells with different chromosome numbers.
- Always discuss your results with a genetic counselor or your fertility specialist.
Frequently asked questions
What does a 'normal' PGT-A result mean?
A normal PGT-A result, also called euploid, means the embryo has the expected number of chromosomes. It does not guarantee a pregnancy or a healthy baby, but it may have a higher chance of implanting compared to an abnormal embryo.
What is a mosaic embryo?
A mosaic embryo has a mix of cells with different chromosome numbers. Some cells may be normal, and some may be abnormal. The clinical significance depends on the specific chromosomes involved and the percentage of abnormal cells. Your genetic counselor can explain what this means for your embryo.
Can a mosaic embryo lead to a healthy baby?
Some mosaic embryos may develop normally, but the outcome is not guaranteed. The risk depends on the type and extent of mosaicism. Your clinic can provide more personalized information based on your embryo's specific result.
What should I do if my PGT-A result is 'no result'?
A 'no result' means the test could not classify the embryo. This can happen for technical reasons. You may discuss with your clinic whether to retest or consider transferring the embryo without further testing. Your clinic will advise based on your situation.
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.
Need help turning research into a shortlist?
