PGT-A (Preimplantation Genetic Testing for Aneuploidy)

Last updated: November 2025

What is PGT-A?

PGT-A involves checking embryos for abnormalities in the number of chromosomes before transfer during an IVF cycle (HFEA, 2021). A small biopsy is taken from the blastocyst, typically at day 5-6, and the cells are analysed.

Does it improve outcomes?

The HFEA Traffic Light system rates PGT-A RED for improving birth rates. Meaning there is no evidence from randomised controlled trials that it helps most patients (HFEA, 2021). It receives a GREEN rating for reducing miscarriage, supported by moderate evidence (HFEA, 2021). A Cochrane Review (CD013602) has examined the available evidence.

Important limitations

PGT-A “often reduces the number of embryos available for transfer” (HFEA, 2021). Mosaic embryos. Those with a mix of normal and abnormal cells, “may be discarded” despite healthy live births being reported from mosaic transfers (HFEA, 2021).

Legal restrictions

PGT-A is not permitted in Germany, France, Denmark, the Netherlands, Sweden, Norway, and Austria (HFEA, 2021). Patients travelling for treatment should confirm legality at their chosen destination. Countries like Spain and the Czech Republic do permit PGT-A.

What to ask your clinic

• What is your clinic’s policy on mosaic embryos?
• How many of your patients’ embryos typically pass PGT-A screening?
• Given my age and history, would PGT-A reduce or improve my chances?

Want to explore clinics that offer PGT-A? Get a personalised quote.

Related research

• PGT-P polygenic embryo screening: what the evidence says: the next frontier beyond PGT-A, screening for complex traits.
• AI vs embryologists: a manufacturer-funded trial found its own product didn’t work: a cautionary tale about embryo selection add-ons.

Sources

1. HFEA. Pre-implantation Genetic Testing for Aneuploidy (PGT-A): https://www.hfea.gov.uk/treatments/treatment-add-ons/pre-implantation-genetic-testing-for-aneuploidy-pgt-a/
2. Cochrane Review. PGT-A (CD013602)

This page is for informational purposes only and does not constitute medical advice. Always consult a qualified fertility specialist before making treatment decisions.