PGT-A in IVF: What the Evidence Shows About Testing Embryos

Not as a routine test for everyone, on current evidence. ASRM's 2024 committee opinion puts it in one sentence: the value of PGT-A as a routine screening test for all patients undergoing in vitro fertilization has not been demonstrated.

That is a strong statement from a body that is not usually blunt, and it refers to routine use rather than every use. PGT-A remains appropriate in defined situations; what is not supported is offering it to everyone.

• It tests biopsied cells, not the whole embryo.
• It selects among the embryos you already have — it does not create more.
• A cycle producing one embryo has little to select between.
• The test costs money and carries a biopsy.

The distinction that matters is between finding a normal embryo faster and having a better chance overall. PGT-A may do the first without doing the second.

Similar outcomes with and without testing. The STAR trial, the largest randomized comparison, found no significant benefit in ongoing pregnancy rate per frozen transfer or per cycle start in women aged 25 to 40.

In women under 35 it went further than neutral: that group showed a decrease in ongoing pregnancy per transfer with PGT-A. Younger patients have more euploid embryos to begin with, so screening has less to find and more to discard on a single biopsy.

The Cochrane review reached the same place from a wider base — 13 trials covering 2,794 patients, rated low to moderate quality, with insufficient good-quality evidence of a difference in cumulative live birth rate, live birth after first transfer, or miscarriage.

'Insufficient evidence of a difference' is not the same as 'proven useless'. It means that after 13 trials, the benefit that would justify routine use has not appeared.

• After a Failed IVF Cycle: What Is Worth Investigating
• IVF Add-Ons: What the Randomized Trials Actually Found
• GnRH Antagonist vs Agonist Protocol — Which IVF Protocol, and Why (2026)
• IVF Success Rates: How to Read the Numbers You Are Quoted
• Endometrial Scratching: What the 1,364-Woman Trial Found
• IVF vs ICSI — What the Difference Is, and When ICSI Actually Helps (2026)
• Consent in IVF: What the ART Act Requires in India

They are the part of PGT-A that has changed most, and they complicate the promise of a clean yes-or-no answer. ASRM notes that mosaic embryos can implant and generate apparently euploid offspring, though they may implant at a lower rate.

An intermediate result may also not reflect the embryo at all. The committee lists statistical variation, amplification bias, contamination, mitotic state and variation in biopsy technique among the possible explanations.

• Mosaic embryos have produced healthy babies.
• An intermediate result may be a laboratory artefact.
• Discarding mosaics may mean discarding viable embryos.
• Clinic policies on abnormal embryos vary — ask what yours is.

ASRM recommends clinics have a written policy on the disposition of abnormal embryos, and that genetic counseling is readily accessible at any point in decision-making. Both are reasonable to ask about before testing, not after.

In defined situations rather than as a default. The argument is strongest where there are enough embryos for selection to mean something, and where the cost of transferring an aneuploid embryo is highest.

• Recurrent pregnancy loss, where the reason is being investigated.
• Repeated implantation failure with good-quality embryos.
• Where a large cohort of embryos makes prioritising them useful.
• Not as a routine add-on for everyone, per ASRM 2024.

The counter-argument to the trials is worth stating fairly. Critics of STAR point out that patients who produced fewer than two blastocysts, or no euploid embryo at all, were excluded — and that a true intention-to-treat analysis would have kept them in the denominator of both arms.

That criticism cuts in a specific direction. Excluding patients who never reached transfer flatters whichever arm they were in, and both sides of the PGT-A argument have used trial design to explain away results they dislike. It is a reason to hold the conclusion loosely, not a reason to assume the benefit is there.

Our article on recurrent implantation failure covers what ESHRE recommends investigating, and egg quality and age covers why aneuploidy rates rise in the first place.

PGT-A is the most heavily marketed IVF add-on, and the claims made for it run well ahead of what the trials show.

• It has not been shown to improve live birth as routine screening.
• A euploid result does not guarantee a pregnancy.
• An abnormal result is not always a non-viable embryo.
• It does not improve egg quality or produce more embryos.

Informed consent, in ASRM's words, should include a thorough discussion of risks, benefits and limitations of the technology used. If the conversation you are having only covers benefits, it is not that conversation.