Preimplantation Genetic Testing (PGT): A Complete Patient Guide

If you are going through IVF, you will almost certainly hear about preimplantation genetic testing (PGT). It is one of the most misunderstood — and most useful — tools in modern fertility care. This guide explains what it does, the three types, and who tends to benefit.

What PGT does

After eggs are fertilized (often with ICSI for male-factor cases), embryos are grown to the blastocyst stage (day 5–6). A few cells are gently biopsied and sent for genetic analysis. The embryo is frozen while results come back. Transfer then focuses on the healthiest embryo.

The three types

• PGT-A (aneuploidy) — screens for the right number of chromosomes. Most embryos from patients over 35 carry some chromosomal mismatch, and transferring a normal (euploid) embryo markedly improves the chance of a live birth and lowers miscarriage risk.
• PGT-M (monogenic) — checks for a specific single-gene condition the parents are known to carry, such as cystic fibrosis or Tay-Sachs.
• PGT-SR (structural rearrangement) — for patients with a balanced translocation or inversion, to avoid passing an unbalanced chromosome set to the embryo.

Who tends to benefit

PGT-A is most often recommended for patients of advanced maternal age, those with recurrent pregnancy loss, repeated unexplained IVF failure, or known chromosomal concerns. For a younger patient with plenty of high-quality embryos, the added value is smaller — and a clinician should talk through the trade-offs rather than defaulting to "yes."

What PGT cannot tell you

It is a screening test, not a full guarantee. It does not assess every genetic disease, and it does not grade an embryo’s developmental potential perfectly. A "normal" result raises the odds substantially; it does not eliminate them. Your care team should be clear about both the upside and the limits.

Fitting PGT into your cycle

PGT adds a biopsy step and a few days of waiting (the embryo is vitrified in the meantime), but it does not change the stimulation itself. If you are considering it, ask how your clinic’s lab validates results and how biopsy experience compares across embryologists. To see how genetic testing sits within a full treatment plan, explore our PGT overview or speak with a physician.