One embryo, one baby: Single embryo transfer

The goal of all fertility treatments should be the birth of a healthy baby with as few risks to the mother as possible. To do this when undergoing in vitro fertilization (IVF), your doctor may advise you to have a single embryo transfer (SET). This means transferring one embryo into your uterus, in order to prevent multiple births.

Your clinic is most likely to suggest SET if you are under the age of 37, have not had unsuccessful treatments before, and have good quality embryos. But this will depend on your individual situation. Staff at your fertility clinic will want to make sure that you have the best chance of having a successful pregnancy and a healthy baby.

Health risks vs. odds of getting pregnant

Did you know?

Multiple pregnancy and birth is the highest risk related to fertility treatments.

Twins or triplets may seem to be the ideal outcome when you are going through fertility treatments. But a multiple pregnancy is the biggest health risk for IVF babies. One in every twelve twin pregnancies results in at least one baby dying or having a significant disability. SET will dramatically reduce your risk of a multiple pregnancy.

You may worry that transferring only one embryo through IVF will reduce your chances of getting pregnant. This is not the case for everyone. In some patients, transferring more than one embryo does not double the chance of success. But it does increase the chance of a multiple pregnancy, with all the inherent risks.

To make sure you are given the best chance, your embryologist will assess the quality of your embryos before the transfer. The best quality embryo will be transferred and other embryos may be frozen and stored for use later. Success rates of pregnancy with SET are similar to those of double embryo transfer(DET), when patients who have the best chance of getting pregnant using SET are carefully selected.

Myths about single embryo transfer

The following are some common misunderstandings about SET and what is involved.

All patients should get SET

SET is not right for everyone. You and your doctor/specialist must decide based on what is best for you. Every clinic has criteria for assessing patients. SET is normally recommended for those who are most at risk of a multiple pregnancy. Many other factors may be also considered, like your age and the quality of your embryos.

SET is designed to save health care dollars

It's not about saving money: it's about saving lives. More than half of all twins and nearly all higher order multiples are born prematurely and are of low birth weight. In some cases, this increases their need for ongoing specialized medical and developmental support. SET is about increasing the number of healthy IVF babies.

Having two embryos transferred will increase my odds of getting pregnant

In the past, IVF patients have sometimes had to take risks and transfer multiple embryos to fix problems getting pregnant. But fertility treatments have improved greatly, so having one embryo transferred no longer means you’re less likely to be successful. For some women, transferring more than one embryo doesn't increase the chance of getting pregnant, but it does increase the risk of a multiple pregnancy. If you are a good candidate for SET, you will have a similar chance of success having one embryo transferred as you would if you transferred two.

I’m healthy and willing to take the risk of having twins

Being healthy does not mean that you will avoid complications related to a multiple pregnancy. Most health risks are because of prematurity, which is more common in multiple births. No one wants to risk the health of their child if it can be avoided.

I know a lot of twins who are perfectly healthy

Many twins are fine, but a great many others are not. For people who conceive without IVF, only 1–2% of pregnancies are multiple. But if you conceive after IVF treatment (when SET is not practiced), nearly 30% of pregnancies are multiple. This means the risks of problem pregnancy, miscarriage, disability, and death are higher. We can decrease the rate of multiple births and maintain a good chance of success by carefully choosing patients for SET.

I’d rather risk a twin pregnancy than not get pregnant at all

Women who become pregnant with twins after transferring two embryos are the same women who are the most likely to have become pregnant after transferring one embryo. If you have concerns about your treatment and the number of embryos you should have transferred, ask to speak with a medical team member at your fertility clinic. They will be able to recommend the best course of action based on your situation.

This information has been adapted from material developed by Infertility Network UK, in conjunction with One at a Time and the Multiple Births Foundation, through a project funded by the UK Department of Health.

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