Should I Do PGT Testing with Donor Eggs?

When it comes to starting or expanding a family, many couples and individuals may turn to assisted reproductive technologies (ART) such as in vitro fertilization (IVF) to help them achieve their goal. One aspect of IVF that many patients are offered– whether using their own eggs or donor eggs – is preimplantation genetic testing (PGT). But is it necessary to do PGT testing with embryos made from donor eggs? Let’s dive in and find out. 

What is PGT?

PGT is short for PGT-A, or “Preimplantation Genetic Testing for Aneuploidies,” and you may also hear it referred to as PGS (“Preimplantation Genetic Screening”) or PGD (“Preimplantation Genetic Diagnosis”) which are various forms of testing embryos. 

PGT testing looks at an embryo to see if it contains the correct amount of chromosomes. Embryos with the right number of chromosomes — 46 — are considered “euploid,” and those with extra chromosomes or chromosome deletions are considered “aneuploid.” PGT is a way to screen for genetic disorders in embryos created through IVF before they are transferred to the uterus. 

PGT testing and age

Here’s an annoying fact: the percentage of embryos that are euploid decreases as we get older. So not only do we have fewer eggs as we age, but the chances that any one egg turns into a healthy baby decreases too.

One study of over 15,000 embryos found that the lowest risk for embryonic aneuploidy was between ages 26 and 30, and that older age groups had the lowest chance of a genetically normal embryo. 

As you can see, chromosomal abnormalities of embryos are normally due to the age of the egg (or rather, the age of the mother or egg donor at the time the egg is retrieved). Since donors are under the age of 33 and healthy, embryos made with donor eggs have a good chance of being genetically normal. So, is it still worth PGT testing donor egg embryos? That leads us to the next section…  

The upside of PGT testing donor eggs

There are definitely some benefits to testing donor eggs:

• Gender selection. PGT testing allows for gender selection. Most clinics allow you to know each embryo’s gender, which can be helpful for families that have a preference.
• Rule out sperm issues. PGT testing of embryos made from donor eggs may also be suggested for couples with male infertility, especially if the sperm has shown chromosome translocations or abnormalities.
• Pick the healthiest embryos. PGT can detect genetic disorders such as cystic fibrosis, Tay-Sachs disease, and sickle cell anemia, allowing for the selection of embryos that do not carry these disorders.

The downside to PGT testing

However, a lot of fertility doctors will say it’s okay to pass on genetic testing with embryos made from donor eggs. Here’s why:

• It’s expensive.The cost of PGT can vary depending on the type of testing done and the clinic you're working with, but it can be thousands of dollars. 
• Added time. It can take some testing companies weeks to give you the results. Time goes so slowly during IVF, and adding additional time can be a major downer. 
• False positives or negatives. PGT can be prone to false positives or negatives, meaning an embryo that is genetically normal could be labeled as abnormal, or vice versa. 
• There’s a small risk to the embryo. The biopsy process, which removes cells from each embryo to be sent for testing, has a chance of damaging the embryo. Also because the embryo must be frozen in order to do PGT testing, there’s risk in having to be thawed and unthawed. 

But the biggest downside is that PGT might not even improve the chances of pregnancy for those using donor eggs! Remember that chart you saw above? If embryos are made from donor eggs, where the donor is under 35… the chances of each embryo being euploid is pretty high. 

Let’s look at the data. A 2020 study looked at 1,291 donor-egg cycles across 47 IVF clinics– 262 cycles with PGT testing and 1,029 without. Live birth rates occurred:

• 53.8% of donor-egg cycles with PGT testing 
• 55.8% of donor-egg cycles with without PGT testing

Yes, you read that right. The donor-egg cycles that skipped PGT actually had higher live birth rates than those who paid to have the embryos PGT tested. The researchers concluded that PGT testing in donor egg-recipient cycles does not improve the chance for live birth, nor does it decrease the risk for miscarriage. But it does increase cost and time for the patient. 

Summing it up

PGT can be a useful tool for patients who are at risk for passing on a genetic disorder or have a family history of a particular condition, however it may not be that useful for those using healthy donor eggs. The financial cost, time, false positives or negatives, and risks to the embryo are all important factors to consider. This is definitely a question and conversation you want to have with your doctor who can help you make the best decision. Good luck!

Cofertility is a human-first fertility ecosystem rewriting the egg freezing and egg donation experience. Our Family by Co platform serves as a more transparent, ethical egg donor matching platform. We are obsessed with improving the family-building journey — today or in the future — and are in an endless pursuit to make these experiences more positive.