Embryos (fertilized eggs) can be frozen in order to be used at a future time. The first baby following embryo freezing was born in 1984. In 2010, a baby was born from an embryo that had been frozen for 20 years. Embryo cryopreservation is the most well-established method of fertility preservation and has the highest pregnancy rates of all fertility preservation treatments.
Embryo cryopreservation requires that the female patient undergo an in vitro fertilization (IVF) cycle with egg retrieval. The eggs (oocytes) are then fertilized with her partner’s sperm or donor sperm and the fertilized eggs (embryos) are then cryopreserved for future use. Importantly, one advantage to embryo cryopreservation is that the embryos do not age while frozen.
The chance of pregnancy remains the same as the pregnancy rate associated with the age of the woman when she did her IVF cycle. If a woman was 23 years old when she cryopreserved embryos and decided to transfer to embryos to her uterus when she was then 38 years old, the chances of pregnancy would be that of a 23 year old, not a 38 year old.
Embryo freezing is usually part of the IVF and embryo transfer strategy when the numbers of high quality embryos exceeds the number required for immediate transfer into the uterus. There are no reports of increased birth defects in pregnancies delivered through this process.