Eggs vitrified for long periods of time keep their quality intact, as demonstrated by a study carried out by Eugin researchers. The group presented the results of the research on Monday at the 38th Annual Congress of the European Society for Human Reproduction and Embryology (ESHRE) held in Milan (Italy).
The study did not record differences in the survival or fertilization rates of vitrified oocytes that were stored between 4 and 8 years compared to those that were kept for shorter periods. According to the researchers, the rates of pregnancy and of the baby born also remained high.
To carry out the research, Eugin scientists analyzed more than 5,000 in vitro fertilization cycles in patients who used previously vitrified donor eggs. This is a technique that is used to save the mature eggs of women who want to use them in the future. It is intended that in the future there will be the same probability of pregnancy as there was at the time that treatment was performed.
Vitrification is the most effective method
“Currently, vitrification is the most effective method to freeze oocytes and preserve fertility. However, as it is a relatively recent technique, which began to be used 10 years ago, the effect of long-term storage of oocytes was not known”, explained Eugin biologist Marc Torra-Massana.
The method used to have vitrified ovules consists of ultra-fast freezing. The ovules must be immersed in liquid nitrogen at -196ºC, so that the cells remain unchanged until they are used. The oocytes are preserved in tanks of liquid nitrogen in the vapor phase.
The use of oocyte vitrification
Oocyte vitrification is used for medical reasons. That is, in patients who undergo very aggressive treatments for their fertility, such as oncological treatments, or gynecological surgeries; and it is also resorted to for social reasons, that is, if the woman decides to postpone motherhood.
This procedure is usually performed for women up to 40 years of age. However, doctors advise it especially for those under 35, who want to be mothers in the future. Depending on the woman’s age at the time of oocyte freezing, the success rate of treatment varies. For this reason, the younger fertility is preserved, the better success rates are recorded.
«The results of this study, in which we have worked for 8 years, represent a further step in the knowledge of vitrification applied to oocyte cryopreservation. It has been shown that it is a good alternative for young patients who need to preserve their eggs long-term, while providing new scenarios in egg donation programs, treatments with a growing social demand”, summarized Torra-Massana.
