Genetic testing in IVF can help answer specific questions about embryos before transfer. It is not one universal test, and it does not guarantee implantation, pregnancy or the birth of a healthy child. The right choice depends on personal and family history, test purpose, evidence, cost and how the result could affect decisions. A fertility specialist and genetic counsellor can help patients understand the options.
What does preimplantation genetic testing involve?
Preimplantation genetic testing (PGT) is performed on embryos created through IVF. At a stage when an embryo has several cells, a small sample may be taken and sent to a laboratory. Embryos are commonly frozen while results are prepared. Testing methods and timelines vary. The result is information about the sampled cells; it cannot assess every genetic or developmental condition, and it is not a substitute for prenatal screening or diagnostic testing during pregnancy.
The main types of PGT
PGT-A looks at chromosome number in the sampled cells. It may be discussed in some cases, but it is not appropriate or beneficial for every IVF patient. Evidence does not show that routine PGT-A improves the chance of having a baby for all patients. PGT-A can be useful in cases of sex selection and cases of family balancing. Results can be uncertain in some cases, including mosaic findings, where sampled cells appear to have different chromosome patterns. The biopsy samples only some cells, so results need careful interpretation.
PGT-M is designed for a specific inherited single-gene condition when the causative variant is known, such as Sickle Cell Disorder. It may be considered when one or both genetic parents carry a condition or have a family history that creates a known reproductive risk. Planning often involves confirming the genetic diagnosis and developing a personalised laboratory test before IVF begins.
PGT-SR assesses embryos for certain chromosome structural rearrangements, such as a translocation, in a genetic parent. It may be discussed when a parent’s chromosome arrangement raises the risk of embryos having an unbalanced chromosome result.
When might testing be recommended?
A clinician may discuss PGT-M when there is a known disease-causing variant and the family wants to reduce the chance of passing on that condition. PGT-SR may be considered when a parent has a chromosome rearrangement. PGT-A may be discussed based on the full clinical picture, but age, previous IVF outcomes or miscarriage history do not automatically mean it is the best option. The likely benefit should be weighed against cost, the possibility of no embryo being classified as suitable for transfer, the chance of an inconclusive or misleading result, and the delay involved.
A person can also choose not to have embryo testing. Depending on the situation, alternatives may include conceiving without PGT and considering prenatal testing, using donor gametes, or other family-building options. A genetics professional can explain what each approach can and cannot establish.
Limitations and follow-up
PGT examines specific features of sampled embryo cells. It does not screen for every genetic condition, guarantee a normal pregnancy, or replace routine pregnancy care. Technical limits can produce false-positive, false-negative or inconclusive findings. For PGT-M and PGT-SR, confirmatory prenatal testing may be offered or considered after pregnancy, based on the test and patient preferences. Discuss the clinic’s policy for mosaic or uncertain results before treatment.
Make an informed decision
Before choosing PGT, ask: What exact condition or chromosome question is this test addressing? What does the evidence say for someone with my history? What are the chances of an inconclusive result or no embryo recommended for transfer? How will results affect embryo storage or transfer decisions? What follow-up testing may be offered in pregnancy? Clear answers help patients decide whether testing fits their values and treatment plan.
For more information, see Nordica’s genetic testing in IVF article, Dr Abayomi Ajayi’s guide to PGT, ASRM’s committee guidance on PGT-M, and HFEA patient information about PGT-A.
