What is the test?
PGT-A tests a few cells taken from IVF embryos (usually at day 5–6) to screen for an abnormal number of chromosomes.
What does it assess?
Chromosome copy number in the biopsied cells, used to help choose which embryo to transfer.
Who might need it?
It is sometimes offered to older patients, people with repeated miscarriage or IVF failure. Suitability should be discussed individually.
When is it performed?
During an IVF cycle, before embryo transfer. Embryos are usually frozen while results are awaited.
How is the test carried out?
An embryologist removes a few cells from the outer layer of the embryo, which are analysed in a genetics laboratory.
How should I prepare?
Ask your clinic about costs, how many embryos are likely to be tested, and what happens to embryos with uncertain results.
What can the results mean?
Embryos may be reported as euploid (expected chromosome number), aneuploid or mosaic. Mosaic results are complex and need specialist discussion.
What are its limitations?
PGT-A does not improve the overall chance of a baby from an IVF cycle for most patients, may lead to fewer embryos being transferred, and the biopsy may not represent the whole embryo.
Is it routinely recommended?
PGT-A is an optional IVF add-on. The HFEA rates evidence as not showing it improves birth rates for most patients.
What happens next?
Review the HFEA add-ons guidance and discuss with your clinic whether it is right for you before paying.
Before paying for additional tests, read the HFEA Treatment Add-ons guidance.
Frequently asked questions
Is PGT-A the same as PGT-M?
No. PGT-M tests for a specific inherited condition known to run in a family; PGT-A screens chromosome numbers.