In IVF cycles usually generates more embroys then needed for one particular embryos transfer. Any excess healthy embryos from the IVF process can be frozen, rather than discarding them into the dustbin. These very frozen embryos can be revived again, process being known as "Thawing", and used for additional attempts at embryo transfer if needed. Process of embryos freezing, 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.
Embryo freezing gives you more opportunities of pregnancy for each hormone stimulation cycle and egg collection.
To avoid serious risks associated with multiple pregnancies, we won’t transfer more than 1-2 embryos at a time. For example, if we manage to obtain more than 2 healthy embryos (this does not always happen), we’ll usually recommend transferring two and freezing the remaining ones. If you do not become pregnant in the first cycle, we can transfer spare embryos in subsequent cycles without making you pass through another cycle of hormone stimulation and egg collection. This process is known as Frozen Embryo Transfer (FET). However, this procedure is taxing for sensitive biological material like embryos and retrieval rate of frozen embryos remains around 50% only.
A unique advantage of embryo freezing is that it preserves fertility potential of a woman which is otherwise bound to go down with advancing age. For example a woman gets her embryos frozen at the age of 30 and utilizes the same at the age of 36, the probability of success in her case will be similar to that of a woman of 30 rather than 36.
Once you have finished your IVF treatment, there are several options available to you. You may choose to store your embryos at our IVF facility, where they will be kept frozen in cryostorage until you decide to either use, donate or discard them.
Once you feel that your family is complete, and you have no further personal use for your frozen embryos, you may decide to donate them to another couple who are unable to conceive with their own embryos. Your specialist can discuss all the options available with you.
Embryos can be frozen from Day 2 (four cell stage) to Day 5 (Blastocyst). They 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 rapidly drops 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.