PGT-A Genetic Screening

PGT-A offers a number of benefits, which some critics may contest, and we’ll cover each of those in this lesson.

First, when PGT-A is used, fewer embryos are transferred that lead to either a failed implantation or a miscarriage. Failed transfers exact an emotional, financial, and temporal toll. Below is data from one clinic that shows when they transfer PGT-A-approved embryos, they have higher rates of implantation, and those implanted embryos are less likely to result in miscarriage.

However, this is not true in all cases. In one study of 600 patients recorded on three continents, investigators showed that using PGT-A to determine which embryo to transfer improved pregnancy rates-per-transfer only in patients aged 35-and-older. For patients under age 35, relying upon the clinic's ability to determine the best embryo by using visual inspection yielded comprable results to using PGT-A.

RMA New Jersey has noticed a phenomenon that we’ve now seen repeated throughout the U.S.: when patients use PGT-A they are more amenable to transferring a single embryo because they have higher confidence that embryo will lead to a live birth, as you can see below.

This matters because multiple embryo transfer carries meaningful risk (as we cover in our Embryo Transfer Course). When a single embryo is transferred, only 1% of births result in twins, but when multiple embryos are transferred, 27% of births result in twins.

Carrying, and delivering, multiple babies is dangerous. Complications during delivery to mother and child increase substantially (2x–5x) with multiple gestation births. These observations are culled from an enormous dataset: every U.S. delivery between 1995 and 2000.

We should say here it's possible to have higher rates of risk and yet still low probabilities a bad outcome will occur. That said, multiple fetuses leads to premature birth, and low birth weight, in 57% of cases for twins and 97% of cases for triplets.

Why does this matter? Low birth weight and premature offspring record lower cognitive scores equating to tens of points on the I.Q. test. In the last month of gestation alone, the baby increases its cortical grey matter by 50% and myelinated white matter threefold.

The authors in the above study also determined, when looking at similar studies, there was a clear correlation with low birth weight, short gestational period, and attention deficit disorder.

Many fertility patients are not just hoping to have one child but to build an entire family through IVF. That may be possible from a single retrieval given most patients who get one embryo from a retrieval actually get multiple.

Now, let’s imagine two scenarios (follow the diagram below) for a family that had their retrieval in January, 2022 and had one viable embryo that could lead to a baby and extra embryos that were all aneuploid, but they know they want more children.

Does PGT-A Testing:

The family tests their extra embryos with PGT-A, realizes none of the extra embryos are likely to work, and does another retrieval cycle in March, 2022. Thereafter, the family transfers an embryo and delivers its first child in December, 2022. Here this family stands with one baby and a new batch of March, 2022 embryos.

Skips PGT-A:

The family decides to transfer their good embryo in March, 2022, the mother conceives and delivers in December, 2022. After a year of recovery, the family decides to transfer their next embryo in December, 2023. That transfer ends in a miscarriage (remember, those extra embryos were aneuploid) in January, 2024. After waiting two months to recover, the family begins their second retrieval in March 2024. Here this family stands with one baby and a new batch of March, 2024 embryos.

Same family, same endpoint (one child already) but staring at the prospect of using embryos derived from eggs of a drastically different age: March, 2022 versus March, 2024. How much does two years matter? That depends on the woman, but in many cases, it’s significant, as you can see by the SART success rates, by age, below.