During the IVF process, following the recovery of the eggs and the creation of embryos, our goal is to see an embryo implant and produce a healthy pregnancy. To reduce the risk of a multiple pregnancy with its inherent risks, we only transfer an appropriate number of embryos to your uterus. As a result, you may have additional embryos that we can freeze (cryopreserve) and store for transfer in a future cycle. Embryo freezing may then provide you with more than one opportunity to conceive from a single egg recovery cycle. However, it is your choice to select this option or not.

Embryo freezing involves laboratory techniques that allow us to store the embryos in liquid nitrogen (-192'c) for potentially very long periods of time. Studies have not shown any increased risk of birth defects from babies born after embryo freezing when compared with those born from maternal age-matched naturally conceived pregnancies. Furthermore, the age-related pregnancy success rates and risk of birth defects corresponds to your age when the eggs were fertilized, not your age at the time you transfer them to your uterus.

Preparation for the transfer of your frozen embryos involves the use of estrogen and progesterone in sequence to create a suitable “lining” layer in the uterus to allow the embryos to implant. Only the strongest appearing embryos are suitable for freezing, but even with this pre-selection, it is possible that some will not survive the freezing and thawing process. Only at the time of expected embryo transfer can we tell you how many embryos have survived the thawing process. Pregnancy rates following the transfer of frozen embryos are lower than those following the transfer of non-frozen or fresh embryos.