PGT-A: Embryo Genetic Testing Before IVF Transfer — Is It Worth It?

PGT-A: what it does, and what the evidence shows

PGT-A checks embryos created through IVF for the correct number of chromosomes before transfer.

How it works

Around day 5 or 6, roughly five cells are removed from the trophectoderm — the outer layer that becomes the placenta, not the baby. The embryo is frozen while testing proceeds, results return in one to two weeks, and a selected embryo is transferred in a later cycle.

That detail about which cells are sampled explains most of what follows.

Does it improve your chance of a baby?

This is contested, and the honest answer is more nuanced than most clinic material suggests.

ASRM (2026) states PGT-A has not been shown to significantly reduce miscarriage or improve live births compared with expectant management, and that patients should be counselled it has not been shown to reduce time to successful pregnancy or increase live birth rate.

The denominator explains why it looks better than it is. Success quoted per embryo transfer looks higher, because only tested embryos are transferred. Cycles where no embryo passed testing have been removed from the calculation. Quoted per cycle started, the advantage largely disappears.

Ask your clinic for their live birth rate per cycle started, not per transfer.

Does it reduce miscarriage?

Partially. ASRM notes that although some observational studies show a reduction, miscarriage still occurs in 10 to 20% of pregnancies after PGT-A.

There is a further point relevant to anyone considering PGT-A because of repeated losses: ASRM notes that patients with recurrent pregnancy loss have a higher likelihood of euploid miscarriage than those with isolated losses, and that likelihood rises with the number of losses. So the group most often offered PGT-A for miscarriage reduction is the group whose losses are least likely to be chromosomal.

Mosaic results

ESHRE states the clinical significance of transferring mosaic embryos is currently unknown. Each centre decides whether to report mosaicism at all, based on its own validation, and must document that policy and share it with you.

Detection is specific to each laboratory's platform and cannot be exchanged between them — so a threshold validated at one laboratory does not transfer to another. Below roughly 20 to 30% of the sample, detection is very difficult.

It selects; it does not improve

PGT-A cannot increase the number of normal embryos you have. It identifies them. If few embryos are available, testing may leave you with none to transfer.

Where it may reasonably be discussed

ASRM notes that in women over 40 with a proven aneuploid miscarriage, it is reasonable to discuss PGT-A using shared decision-making — with the counselling caveats above.

Whatever the result

ESHRE recommends prenatal diagnosis is offered to all women who become pregnant following PGT. A euploid result is good information, not a final answer.