Step 5: Embryo transfer to the womb

Eggs that have fertilised are called embryos. We transfer embryos to your womb 2, 3 or 5 days after fertilisation.

During embryo transfer, we put the best 1 or 2 embryos into your womb. This is a much simpler procedure than egg collection and there is no need for sedation.

We use an ultrasound scan probe on your tummy. This is a small device that gives off high-frequency sound waves. The waves create a picture of the inside of the womb. We can then put the embryos where they have the best chance of attaching to the womb lining (implantation). 

Preparing for embryo transfer

You need to have a full bladder for the procedure. This allows us to see your womb (uterus) clearly on the ultrasound scan. A full bladder also makes it easier for us to put in a small plastic tube (soft catheter) containing the embryos.

A nurse or embryologist explains how to prepare for the embryo transfer.

Transferring the embryo

We ask you and your partner or donor (if you come to the hospital together) to give your names and dates of birth before the transfer. The doctor and embryologist check that the dishes containing your embryos are labelled with your name and unique identity number. 

The embryologist (a fertility treatment scientist) selects the best embryos for transfer. The doctor and the embryologist discuss this with you. 

We put a speculum, the small device used for cervical screening, in the vagina to help us see the cervix clearly. Your cervix is the opening between the vagina and the womb.

We clean the outside of the cervix and remove any mucus from inside the cervical canal (a passage through the cervix). This mucus might prevent the embryos from getting to where they should be in the womb. 

We put the soft catheter holding the embryos into your womb. Usually, we try this with an empty catheter first to find the best position and path. Then, we gently place the embryos into your womb.

We remove the catheter and check that the embryo(s) have been transferred. 

You can empty your bladder immediately after the transfer without any risk of losing the embryos. 

Frozen embryo transfer

In a frozen embryo transfer cycle, we thaw some of your frozen embryos and transfer 1, 2 or 3 of them into your womb. We talk to you in advance about how many embryos will be thawed. 

The successful rate of frozen embryo transfer depends on your age at the time of freeze and embryo quality, and our doctors will be able to advise you individually.

An advantage of a frozen embryo transfer is that you do not need hormone injections to help you produce eggs. Also, you do not have a surgical egg collection procedure. 

For more information about a frozen embryo transfer, please speak to a member of our team. 

If you have frozen embryos, it is essential that you keep in touch with us. You need to let us know what you want to do with them and tell us about any changes of address. 

Transferring blastocysts

By day 5 after egg collection, the cells of embryos have divided and multiplied to become blastocysts. 

You are most likely to benefit from blastocyst transfer if you have both:

• a good chance of getting pregnant
• a risk of a twin pregnancy if we transfer 2 embryos

If we transfer a single embryo, we hope to reduce the chance of twins without affecting the overall chance of pregnancy. 

How many embryos are transferred

If you are under 35 years and in your first cycle, we will usually transfer 1 embryo to your womb. This is especially likely if there are extra embryos for freezing. It gives you a high chance of pregnancy (over 50%) and a low chance of twins.

If you are older than 35 or if the embryo quality is not as good, we might transfer 2 embryos to your womb.

If you are aged 40 or over, we will talk to you about whether we think you should have 3 embryos transferred. 

If the remaining embryos are suitable, we will freeze them for future use. 

Taking a pregnancy test

We give you a pregnancy test kit and explain how to use it. You need to take the test 16 days after your egg collection. We tell you the date at your embryo transfer.

It is important to take a pregnancy test 16 days after your egg collection, even if you bleed before this time. Some people who bleed after a cycle could have an ectopic pregnancy. This is when a fertilised egg attaches (implants) itself outside of the womb. It cannot develop into a baby and your health may be at risk if the pregnancy continues. This is an uncommon but serious complication of IVF.

You need to email or phone the assisted conception unit (ACU) to give us the result of your pregnancy test. 

Please do not take the pregnancy test earlier than the date that we give you. We know that this wait can be difficult. However, the trigger injection that you had before egg collection can stay in your blood stream for 8 to 10 days. It can make the test positive, even if you are not pregnant. 

There is no evidence that anything you do at this stage increases the chances of pregnancy. We encourage you to return to work, but you might prefer to have a few days off around the time of embryo transfer.

Having baths or sex does not affect the chances of pregnancy.