PGT-A (Preimplantation Genetic Testing for Aneuploidy)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

PGT-A (Preimplantation Genetic Testing for Aneuploidy) is a laboratory procedure performed on an embryo biopsy during IVF to screen for chromosomal aneuploidy before transfer. Cells are removed from the trophectoderm of a blastocyst and analyzed by next-generation sequencing or array comparative genomic hybridization to determine chromosomal copy number. Embryos classified as euploid (chromosomally normal) are selected for transfer; aneuploid embryos are typically discarded or frozen and not transferred.

PGT-A is marketed as a tool to improve IVF success rates by transferring only chromosomally screened embryos. The evidence for routine use in good-prognosis patients does not support that claim. A multicenter randomized clinical trial (the STAR trial, Fertil Steril 2019) assigned 661 good-prognosis patients to either PGT-A-based embryo selection or morphology-based selection. By intention-to-treat analysis, ongoing pregnancy rates at 20 weeks were 41.8% in the PGT-A group (138/330) versus 43.5% in the morphology group (144/331). The difference was not statistically significant.¹

The mechanism behind this finding is important to understand. PGT-A can improve per-transfer success rates by removing aneuploid embryos from the queue. It does not improve cumulative outcomes because it simultaneously reduces the number of embryos available for transfer. Embryos discarded as aneuploid include a proportion of mosaic embryos: those with both normal and abnormal cells. Mosaic embryos have produced healthy live births. The decision to discard them based on trophectoderm biopsy results carries clinical and ethical weight that the per-transfer success metric does not capture.¹

PGT-A is specific to IVF. It applies only when embryos are created outside the body and biopsied before transfer. Natural conception, which RRM supports and facilitates, does not involve embryo creation outside the body, embryo biopsy, or chromosomal selection. The question PGT-A is designed to answer does not arise in restorative care.

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.