Since the first pregnancy with cryopreserved embryos in 1983, the progress in the field of cryogenics has been rapid and now allows the cryopreservation of the embryos, as well as gametes (eggs and spermatozoa).
The evolution of cryobiology has contributed towards:
New method of cryopreservation: Vitrification
In recent years, great strides have been made in the field of cryobiology with the greatest achievements being the possibility of cryopreservation of male and female gametes (eggs and sperms), as well as embryos and stem cells.
The process of vitrification is a very successful freezing method and is achieved by using high concentrations of cryopreservative substances and the very rapid reduction of the temperature up to -196°C. The cooling rate of eggs -embryos reaches 20.000°C per minute, thus preventing the formation of intracellular water crystals, which causes extensive “damage” inside the cells.
The success rates of vitrification are very high compared to older methods of cryopreservation. It is now possible to freeze eggs with high survival, fertlization and implantation rates after thawing. According to the literature, pregnancies from cryopreserved oocytes can exceed 15%. So far, 300 children worldwide have been born with this method.
With regard to embryos, we expect a significantly higher pregnancy rate per embryo transfer of over 35-40%. The freezing process can take place on the 5th-6th day (blastocyst) with equally high pregnancy rates per embryo transfer of over 27%.