Definition - What does Frozen Embryo mean?
Frozen embryos are good quality embryos that have been preserved for potential future use. Because of the cumulative nature of pregnancy, multiple embryos are often created during an in vitro fertilization cycle to increase the chances of achieving pregnancy. Any embryos that are not directly transferred to a uterus can be cryopreserved for future pregnancy attempts.
Additionally, embryos can be frozen for a number of different reasons including not being ready to have children or the discovery of a medical condition that will negatively impact fertility.
FertilitySmarts explains Frozen Embryo
Embryos are typically frozen between a four-cell stage and a blastocyst— day 2 to day 5. After being sealed and labeled, and water is drawn out to protect the embryo, they are frozen to -150 degrees Celsius and then stored in a tank of liquid nitrogen at -196 degrees Celsius.
There is no significant difference in live-birth rates between fresh and frozen embryo transfers. Frozen embryo transfers can also lower the risk of ovarian hyperstimulation syndrome (OHSS)
The process was developed in the 1980s and while most embryos are stored for a few months to a few years, they can be stored for longer. In 2017, a healthy baby girl was born from an embryo which had been frozen for 24 years.
Frozen embryos are typically kept in cryostorage at IVF facilities until the owners decided what to do with them. They can choose to use the embryos for future pregnancy attempts, they can donate them to other couples, or to research, or have them discarded.