Frozen Embryo Transfer (FET)
Definition - What does Frozen Embryo Transfer (FET) mean?
A frozen embryo transfer (FET) is procedure where embryos that were cryogenically stored (frozen) from a previous IVF or donor egg cycle are a thawed and transferred to a uterus as part of an in vitro fertilization (IVF) cycle.
After the lab development of the embryos for 1-6 days, cryopreservation for times ranging from days up to several years, hormonal treatments to prepare the uterine lining to receive the embryo, and thawing of the preserved embryo is followed by transfer to the uterus. Progesterone may be prescribed following the procedure.
FertilitySmarts explains Frozen Embryo Transfer (FET)
In 1984, the first child was born from a previously frozen embryo. Initially, the success rate for this method was low. As the technology improved, so did the results. A 2009 review comparing fresh embryo transfer and frozen embryo transfer found as good or better outcomes for frozen embryo transfer. The health of the infants was not adversely affected by embryo cryopreservation.
A 2016 study by the U.S. National Assisted Reproductive Technology Surveillance System advised that, for many women, sequential single embryo transfers (with the first embryo fresh and the second embryo frozen) can achieve the same or greater number of live births as double embryo transfers at a lower cost by avoiding the risks associated with multiple births.
Success rates are primarily impacted by the age of the mother at the time of freezing.