Freezing Embryos

Any excess healthy embryos from the IVF process can be frozen, in case more than one treatment cycle is needed. Freezing embryos, also known as cryopreservation, takes place for some 60% of all patients having IVF treatment – and frozen embryo transfers accounts for around 50% of all IVF births in our program.

The advantages of freezing embryos

Embryo freezing provides more opportunities for a pregnancy for each hormone stimulation cycle and egg collection.

During a typical IVF cycle, we’ll be able to create more than one or two embryos. But we don’t want to transfer them all, as there are serious risks with multiple pregnancies.

So, embryo freezing increases the chance of a pregnancy for each cycle. As an example, if we obtain six normal embryos we’ll usually recommend transferring one or two, and freezing the others. If you do not become pregnant in that first cycle, we can transfer another two embryos, without you having to undergo another cycle of hormone stimulation and egg collection.

Storage by freezing embryos is intended to be short term, but we can store embryos for a long time, if needed.

Once you have finished your IVF treatment, you may choose to donate your frozen embryos to another couple who are unable to conceive with their own embryos. Your specialist can discuss all your options with you.

How does embryo freezing work?

The embryos are placed in thin plastic straws, sealed at both ends, and labelled with your name and identification number. They then go into a freezing machine, where the temperature gradually goes down to -150° Celsius. The straws are then placed in goblets, and put into tanks filled with liquid nitrogen, which keeps the temperature at  -196° Celsius.

Success rates with frozen embryos

At Hunter IVF, many of our births, over many years, have come from the transfer of frozen and thawed embryos.

The main factor for success is the age of the woman’s eggs when the embryos are frozen. This means you could freeze your embryos in your first IVF cycle at the age of 38, and if you then use them when you’re 42 (for example, you’d like another baby) your fertility chance will be that of a 38-year-old woman rather than a 42-year-old.

Find out more about our fertility preservation program

Contact us for more information about freezing embryo and embryo transfer

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