PGT-A (Preimplantation Genetic Testing for Aneuploidy)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 7, 2026

Preimplantation genetic testing for aneuploidy (PGT-A) is a laboratory test performed on an embryo biopsy during IVF to screen for chromosomal aneuploidy before transfer. Formerly called PGS (preimplantation genetic screening), PGT-A is marketed as a tool to improve IVF success rates by selecting only chromosomally normal (euploid) embryos for transfer. The evidence for routine use in good-prognosis patients does not support the marketing claim. The STAR trial, a multicenter randomized controlled trial in good-prognosis IVF patients, found no significant difference in ongoing pregnancy rates at 20 weeks between PGT-A selection and morphology-based selection alone: 41.8% (138/330) with PGT-A versus 43.5% (144/331) with morphology, by intention-to-treat analysis.⁵⁹ PGT-A improves per-transfer success rates by removing aneuploid embryos from the transfer queue, but it does not improve cumulative outcomes because it simultaneously reduces the number of embryos available for transfer. An additional concern: embryos classified as mosaic (partially aneuploid) are often excluded from transfer, yet mosaic embryos are capable of producing healthy pregnancies. PGT-A is specific to IVF. RRM does not involve embryo creation outside the body, embryo biopsy, or embryo selection. The question of which embryo to transfer does not arise in RRM practice.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.