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 account for around 50% of all IVF births in our program.
Why do we freeze embryos?
Embryo freezing provides more opportunities for a pregnancy from each IVF stimulated cycle. For example, if a number of normal embryos are obtained in an IVF cycle, we might suggest transferring one or two of them and freezing the other four or five. This would generally allow further embryo transfers in later cycles without the need to undergo a full stimulated IVF cycle if pregnancy did not occur in the first cycle. If a baby is conceived in the stimulated IVF cycle then the frozen embryos can be used subsequently to try for another pregnancy without the need for further hormone stimulation
Embryo freezing gives 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 embryo, however, there are serious risks associated with multiple pregnancies, so generally, we won’t transfer more than one embryo at a time.
For example, if we manage to obtain two or three normal embryos (this does not always happen) we’ll usually recommend transferring one and freezing the others. If you do not become pregnant in that first cycle, we can transfer another embryo.
This is called a Frozen Embryo Transfer (FET) and means you won’t have to undergo another cycle of hormone stimulation and egg collection.