The advent of vitrification technology (or rapid freezing) allowed not only to freeze eggs, but also to successfully fertilize them after defrosting. According to the latest data, the efficiency of fertilization of vitrified oocytes is comparable to fresh ones. This gave a new chance to women suffering from oncopathology to preserve their fertility before starting treatment, as well as for women who are not planning pregnancy at the present time, to give birth to their own child genetically in the future.
The number of oocytes in women is predetermined by nature and individually in each case. On average, by the time of puberty, the number of eggs is about 250-300 thousand. Over time, their number decreases. The rate of follicle depletion only increases with age. So, after the age of thirty-five, the number of eggs in the female body is about 25,000, and by the time of menopause it is already about 1,000. On average, only 400-500 eggs from the entire initial stock ovulate throughout a woman’s life
A sharp decrease in the number of oocytes leads to the fact that after 35 years the probability of fertilization in each cycle is significantly reduced. In addition, changes in the oocytes themselves occur with age, which leads to possible genetic breakdowns, and, as a result, to the likelihood of having a child with genetic disorders.
The modern rhythm of life, economic situation, career, and sometimes medical indications lead to the fact that many women postpone motherhood until “better times”. It happens that when this time comes, women face the problem of pregnancy, even through IVF. Of course, the alternative may be to use donor oocytes from a young donor, but many still prefer to have a genetic child of their own. Until recently, this was an unsolvable problem.
During normal cryopreservation, oocytes were destroyed and only a new vitrification method allowed them to be successfully frozen, thawed, and, if necessary, re–frozen again. What is vitrification? This is a fast freezing procedure in which an oocyte at room temperature of the body is placed in a cryoprotective medium of high concentration and is directly exposed to liquid nitrogene. This rapid freezing prevents the formation of ice crystals inside the cell, which would destroy it. An oocyte frozen in this way can be stored for decades. At the same time, the age and quality of the egg remain the same as they were at the time of puncture.
This procedure has already allowed many women to give birth to their own healthy child even after undergoing chemotherapy and radiation therapy due to cancer.
Are there any maternal risks associated with this procedure? As with any IVF procedure, there are minor risks associated with stimulation of superovulation and ovarian puncture. Modern stimulation protocols, as well as puncture under ultrasound control, allow them to be minimized. World experience shows that children born after vitrification of oocytes do not differ from children born in fresh cycles.