Genetic Testing of Embryos in Patients Under Age 35

Patients often ask about the use of genetic testing of embryos and wonder if this is something that would increase their success rates during IVF. Genetic testing of embryos called preimplantation genetic testing for aneuploidy (PGT-A) is the terminology to describe a biopsy of the outside of the embryo (future placental cells called the trophectroderm) that evaluates the number of chromosomes in a few cells. This is a screening test for some things such as Down syndrome but is unable to detect other aspects such as other genetic and metabolic defects, birth defects or autism.

This technology does have some limitations including likely a small risk to the embryo from the biopsy itself. It is best utilized as a tool in women over 35 to help us to select which embryo to transfer first. Its utility in women under age 35 has been debated and a recent study helps us to look at this further.

This study evaluates the success rates of IVF using PGT-A in patients aged 21-40 years undergoing single embryo transfer. The study aimed to compare live birth rates between cycles using PGT-A and those using the grading system of embryos alone.
PGT-A was associated with a slightly lower live birth rate in patients under 35 years. In comparison, PGT-A was associated with a higher live birth rate in patients aged 35-37 years and 38-40 years. The miscarriage rates were significantly lower in patients aged 35-40 years using PGT-A compared to those not using PGT-A. ( Harris, Benjamin et al. Fertility and Sterility 2025).

The study concludes that the benefits of PGT-A are age-dependent, with significant advantages in older patients (35-40 years) but not in younger patients (<35 years). The findings suggest that PGT-A may be beneficial for patients aged 35 years and older, potentially reducing miscarriage rates and improving live birth outcomes. This is consistent with what we see in our own lab. When we evaluate a risk-benefit ratio, PGT–A does not improve overall success rates in under age 35 patients. Your doctor will of course evaluate your specific case and potential exceptions to this could include recurrent pregnancy loss and when we are also evaluating for a single-gene disorder (with preimplantation genetic testing for monogenic disease).

By Dr. Jessica McLaughlin