Single Embryo Transfer (SET): Everything You Need to Know

happy expecting couple sitting on a couch

Finding the right fertility treatment can be confusing. We know you’re probably exploring all things fertility to better understand the various treatment options. You have most likely heard of a Single Embryo Transfer (SET) but may have more questions. We sat down with Jennifer Hart, Laboratory Manager and Senior Embryologist at STL Fertility, to take a deep dive into SET and learn why more people continue to pursue this option.

Here’s what she had to say:

I’m considering SET but have some reservations, can you tell me more about it?

Single Embryo Transfer (SET) is a procedure that involves placing one embryo into a patient’s uterus to initiate a pregnancy. It is the final step in an IVF cycle, and one of the many ways that people who endure challenges on the path to parenthood choose to conceive.

One of the greatest misconceptions surrounding SET is that it decreases your chances of getting pregnant. People incorrectly assume that transferring more embryos results in a higher chance of a healthy pregnancy. However, with advancements like PGT-A, TE biopsy, and endometrial synchrony, we can now achieve higher success rates using SET than by transferring multiple embryos. In the past, many IVF centers have implanted two or more embryos into the uterus in an attempt to increase the odds of pregnancy, but this puts patients at a dramatically higher risk for complications during pregnancy.

Why would I want to risk SET when I could do a multiple embryo transfer and increase my odds?

While there are rare cases in which multiple embryo transfer is a better option for a patient, SET is the preferred method for multiple reasons. With SET, the likelihood of parenting twins, triplets, and so on, decreases substantially.

Although some IVF patients believe they might welcome the idea of a multiple pregnancy, many people do not fully comprehend the implications to both themselves and their babies.

Twin and triplet IVF pregnancies carry substantially increased risks of preterm labor, pre-eclampsia, and premature birth.  There are many complications that can make any pregnancy risky.  Twin and triplet pregnancies greatly increase the chance of pregnancy complications as well as the gravity of these complications.

But what are the odds that the one embryo I use for SET establishes a pregnancy?

Pregnancy rates vary based on the different circumstances brought by both partners.  The chance of initiating a pregnancy after an embryo transfer does not increase by transferring more than one embryo. Once the laboratory has chosen the best embryo available for transfer, the chance for establishing a pregnancy can be as high as 70% depending on patient age and diagnosis. Advancements like PGT-A are one of the tools used for embryo selection, when indicated.  PGT-A is Preimplantation Genetic Testing for Aneuploidy.  It involves taking a biopsy of an embryo and having that biopsy analyzed before implantation. This test is looking to see that the single embryo being used has 23 pairs of chromosomes.

An abnormal copy number for any chromosome would be diagnosed as “aneuploid” or abnormal. Most aneuploid embryos are not compatible with life and will end in miscarriage or don’t implant at all. There is a small percentage of aneuploid embryos that are compatible with life but will lead to disorders such as Down syndrome or Turner syndrome. Embryos with 23 pairs of chromosomes are diagnosed as “euploid” or normal.

PGT-A allows an embryologist to identify embryos as normal vs abnormal, and gives patients their very best attempt at a healthy pregnancy. PGT-A can only test for copy number of chromosomes, so if a patient has more than one embryo that is euploid, the embryologist uses an embryo grading system to rank the available embryos, giving priority to the one with the highest grade.

When a single, euploid embryo is transferred, the patient has her highest potential for establishing a pregnancy.

Many patients worry that their embryos must be sent out for PGT-A, but this is not true. The embryos will stay frozen in the clinic and the biopsy (which consists of several cells from the embryo’s trophectoderm) will be shipped to the genetic testing lab for analysis. The embryos never leave the laboratory.

What else makes a singleton birth desirable for me, as a patient?

A healthy singleton birth is the goal for all patients as it is the best option for the mother and child. Although many of our patients are beyond anxious to grow their families, it’s in everyone’s best interest to do it in the safest way. We can now achieve similar success rates when one screened embryo is transferred versus two unscreened. Screening the embryo can make all the difference.

A singleton birth requires the shortest amount of recovery time and are associated with lower complications when compared to twin and multiple gestations.

In what instance would SET not make sense?

For patients that have had repeated failures with SET, they may reach a decision with their physician to transfer two embryos at one time.

Is PGT-A typically covered by insurance?

Unfortunately, PGT-A is not often by traditional covered by insurance. The good news is that PGT-A is almost always covered by Progyny, meaning all patients can PGT-A test their embryos without paying out of pocket

How do I find out if I have coverage for PGT-A for my SET cycle?

As always, contact your Progyny Patient Care Advocate (PCA) for more information about your benefit and for assistance getting started!

Still curious about SET? Hear from more experts: How Many Embryos Should You Transfer?