Elective Single Embryo Transfer (eSET) Explained

Is two better than one? When it comes to the number of embryos you transfer in your IVF cycle, maybe not. Elective single embryo transfer (eSET) is becoming a more popular choice, and for good reason. After all, it only takes one - and one may be the safest way to go.

What is eSET?

Elective single embryo transfer (eSET) is the intentional transfer of one embryo when there are multiple embryos of appropriate stage and quality available. This is different from obligatory or non-elective single embryo transfer, when only one embryo is available. It is a choice made by the intended parents, under the guidance of their doctor, because it means that they technically have the option to transfer multiple healthy embryos.

Pros and cons of elective single embryo transfer

The very first successful birth through in vitro fertilization back in 1979 resulted from a single embryo transfer. Over the years, however, the attitude began to shift; if more than one healthy embryo was available, why not transfer two? Double embryo transfer (DET) became the norm. And if only lower grade embryos were available – meaning less chance of a successful pregnancy - some doctors would transfer even three or four at a time.

While transferring more embryos did ultimately result in better pregnancy rates, it also meant greater risks. There was a marked increase in triplet pregnancies – sometimes even more. Remember “Octomom”? Her pregnancy with octuplets was the result of a doctor inserting 12 embryos in one transfer. While it was called an “extreme departure from standard of care,” it was an example of the attitude surrounding embryo transfer and launched an ethical debate about creating a new standard for IVF.

The decision to transfer multiple embryos is often financially motivated. IVF is an expensive undertaking, and many couples simply don’t have the means to fund multiple cycles. They think transferring two or three embryos will give them a greater shot at success in one go, even though live birth statistics don't support this.

States that have mandated IVF insurance coverage laws – meaning less financial burden on intended parents – have fewer high-order multiple births, fewer preterm births, and fewer low birth weight infants as compared to states without mandated coverage. It can be argued that this reflects less pressure to succeed in one transfer, and ultimately results in healthier babies.

A pregnancy with multiples is higher risk than with a singleton, and IVF patients are already 20 times more likely to conceive twins. Rather than intentionally put a mother and babies in greater jeopardy, experts argued, why not utilize improved technology like Comprehensive Chromosome Screening (CSS). This form of genetic screening counts the total chromosomes and, while it’s not as comprehensive as preimplantation genetic testing (PGT), it is an accurate method to select the highest quality embryo for transfer.

The benefits of eSET are plentiful for the baby; studies find that, in conjunction with CSS, single embryo transfer babies were half as likely to be born prematurely, a third less likely to be low-birth weight, and less likely to spend time in the neonatal intensive care unit (NICU) at birth compared to double embryo transfer multiples.

How to know if you are a good candidate for eSET

There are several factors that could make eSET an especially attractive option for you:

Your cycles result in several high quality embryos. High quality embryos are more likely to result in a pregnancy, meaning there is no need to transfer more than one.

You’re 35 years old or younger. Egg quality starts to decline after 35, which means you may not have as many high quality embryos to work with. According to the Society for Assisted Reproductive Technology (SART), the percentage of women who chose single embryo transfer is greatest among women under 35.

You have donor eggs. If you’re using an egg donor, you know the eggs are of the highest possible quality. Donor eggs result in the best live birth rates of all treatment, particularly when used with a surrogate.

It’s important to have this discussion with your doctor to determine the best option for you; one that will get you closer to a baby while also protecting everyone’s best interest. As an article in the Contraception and Reproductive Medicine journal pointed out, “When the goal is to minimize IVF complications, multiple embryo transfer does not necessarily translate to a superior outcome. The future success of assisted reproductive technology (ART) lies in elective single transfer; the power of one.”

If you have questions about how utilizing an egg donor or gestational carrier can help you in your own ART success, contact our team for guidance.