- Elective single embryo transfer (eSET) is the transfer of a single embryo generated through in vitro fertilization (IVF) into the mother’s uterus for pregnancy, even when multiple healthy embryos are available.
- Whenever possible, the goal in fertility medicine is the birth of a single healthy child. eSET aims to decrease chances of twins or more, which is known as a multiple pregnancy.
- A multiple pregnancy increases certain health risks for the mother such as pregnancy-induced hypertension and gestational diabetes. It also increases the risk of early labor, and premature birth can cause risks for the child such as long-term health and developmental conditions.
- Advances in embryology and clinical techniques have increased the success rates for single embryo transfers, which in many circumstances are now similar to birth rates when multiple embryos are transferred. This has made eSET the standard.
What is eSET (elective single embryo transfer)?
Elective single embryo transfer (eSET) is the transfer of just one IVF embryo into the mother’s uterus, even when additional healthy (viable) embryos are available. With eSET, the goal is to achieve a healthy birth of a single baby (a singleton) with each IVF cycle to reduce the chance of a multiple pregnancy of twins or more. The American Society for Reproductive Medicine (ASRM) also recommends this as a goal in embryo transfer.
Why eSET with IVF is the new standard
With IVF, women take medication to stimulate egg production, often resulting in the retrieval and successful fertilization of more than one egg, meaning more than one embryo. Historically, multiple embryos were then implanted to increase the prospect of a pregnancy and subsequent birth via IVF. This was standard practice for most IVF patients.
As technology improved, transferring multiple embryos led to about 30% of IVF pregnancies in the United States being twins and an additional 3%-4% being triplets or more. The high rates of multiple pregnancies led to a re-examination of multiple embryo implantation due to the concern for the health of mother and child.
Health concerns for the mother due to multiple pregnancy include:
- Placenta previa along with other problems of the placenta and increased risk of hemorrhaging.
- Emotional stress including increased feelings of depression and low self-esteem post-delivery.
- Increased risk of gestational diabetes.
- Preeclampsia (high blood pressure).
- Need for cesarean section.
- Risk of losing the pregnancy.
- Need for bed rest or hospitalization.
Health concerns for the babies in a multiple pregnancy include:
- Need for intensive care after birth.
- Increased mortality rates (death).
- Low birth weight.
- Developmental disabilities including cerebral palsy, deafness, blindness and respiratory problems.
Accompanying the concern about health risks from multiple pregnancy, advances in assisted reproductive technologies (ART) improved the selection of the best embryo and successful implantation rates for single embryo transfers in IVF, which continue to improve. Now eSET is the IVF standard to help avoid the health risks of multiple gestation to mom and baby.
Learn more about single embryo transfer: Jessica and Phillip’s fertility story.
Common questions about eSET
- How is the best embryo chosen? If your embryos are not genetically tested, our IVF laboratory grades the embryos based on their appearance. The development rate, number and size of cells, and other factors are assessed. The most viable embryo is then chosen for transfer.
- How successful is eSET in avoiding a multiple pregnancy? eSET dramatically lowers the rate of IVF twin pregnancy from 30% to 1%-2%.
- What happens if I do not conceive with the first embryo? After the best embryo is chosen, the patient can elect to freeze any remaining embryos that are viable for future implantation procedures without starting from the beginning of the IVF process.
Benefits of eSET
The Centers for Disease Control and Prevention says women who are suitable candidates for eSET experience pregnancy and live birth rates similar to women who choose to transfer multiple embryos. Almost all eSET pregnancies are singletons, helping many mothers and their babies avoid medical complications, although twins are still a naturally occurring event and possible even when only a single embryo is transferred.
Although a woman or couple undergoing IVF may want to maximize their chances of success by implanting multiple embryos, we encourage eSET as a very effective option. Fewer embryos transferred does not mean lower success rates.
Who should consider eSET for IVF embryo transfer?
The best candidates for eSET are women who are:
- Younger than 35 years.
- Undergoing their first ART cycle or have had a successful pregnancy in a prior ART cycle.
- Have a comparatively large number of high-quality embryos available for freezing (or already frozen) to use in a later cycle.
- Availability of genetically tested (PGT) normal embryos for transfer.
Other considerations for eSET
ASRM has published guidelines on how many embryos to transfer in different age groups, recommending women 35 years or younger who have eggs or embryos of good quality to pursue single embryo transfer and freeze the remainder. eSET is also an appropriate option for women with a favorable diagnosis such as male factor infertility or isolated tubal infertility.
ASRM guidelines may recommend multiple embryo transfers for some women due to age or specific conditions. However, all women, regardless of age, are permitted by Dallas IVF to have an eSET if they would like to minimize the risk of multiples.
Women should also contemplate their health risks when considering eSET. For example, a woman with a uterine anomaly would be placed at higher risk for preterm birth if she were to conceive twins. Many medical diseases may also be significantly worsened by twins. Women facing these concerns should consider eSET, even if they do not have a favorable prognosis otherwise.
The same IVF process with eSET
The eSET procedure follows the basic flow of IVF. The woman’s eggs gathered during IVF are fertilized and the embryos mature in the fertility lab (outside the body) for up to five days. At that point the embryologist chooses the highest quality embryo to transfer based on multiple factors.
This may include information learned from preimplantation genetic testing (PGT). This evaluation identifies genetic flaws in embryos that not only lead to birth defects, but are also a major cause of implantation failure and pregnancy loss.