Published online by Cambridge University Press: 24 December 2019
The first live births following frozen-thawed embryo transfer were reported in 1984 and 1985 by groups in Australia, the Netherlands and the United Kingdom. Since that time, the original protocols have been modified and simplified such that cryopreservation with successful survival of sperm, oocytes and embryos is now an essential component of every routine IVF program. Pregnancy and live birth rates after frozen embryo transfer contribute significantly to cumulative conception rates after fresh transfer. In recent years, traditional methods of freezing and thawing have been increasingly replaced by protocols for vitrification/warming. For both slow freezing and vitrification, an understanding of the basic principles of cryobiology involved is essential to ensure that the methodology is correctly and successfully applied, in order to minimize cell damage during the processes of freezing/vitrification and thawing/warming.