During the In Vitro Fertilization (IVF) process, following the retrieval of the eggs and the creation of embryos, our goal is to see an embryo implant and produce a healthy pregnancy. 

To reduce the chance of a multiple pregnancy and its inherent risks, we only transfer an appropriate number of embryos into a woman’s uterus. As a result, a patient may have additional embryos that can be frozen (cryopreserved) and stored.

Embryo freezing provides a patient with the opportunity to conceive more than once from a single egg recovery cycle.

Embryo freezing involves laboratory techniques (cryopreservation) that allow us to store the embryos in liquid nitrogen for very long periods of time. Studies have not shown any increased risk of birth defects in babies conceived using frozen embryos compared with those born of naturally conceived pregnancies from mothers of a similar age.

Furthermore, age-related pregnancy success rates and birth defect risks correspond to the age of the eggs themselves (determined by the age of the patient when the eggs were fertilized) and not to the age of the patient when they were transferred into the uterus.

Preparation for the transfer of frozen embryos involves the use of hormone medications (estrogen and progesterone) in sequence to create a suitable “lining” layer in the uterus, which allows the embryos to implant. Only the strongest 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 are patients informed about the number of embryos that have survived the thawing process.
Pregnancy rates following the transfer of frozen embryos are similar to those following the transfer of non-frozen, or fresh embryos.