The advent of vitrification technology (rapid freezing) allowed not only to freeze eggs but fertilize them well after thawing. According to recent reports, the effectiveness of vitrified oocytes fertilization is comparable to fresh. This has given a new chance for women suffering from cancer to preserve their fertility before treatment started, as well as for women who are not planning a pregnancy at present, to have a genetic own child in the future.
The number of oocytes in women is determined by nature and can vary in each case. On average, when the woman became sexually mature the number of oocytes is about 250-300 thousands. Over time pass a number of eggs decreases. The rate of depletion of follicles with age only increases. So, after thirty-five years of age the number of eggs in the female body is about 25,000, and by the time of menopause for about 1000. On average, over the life of the woman ovulates only 400-500 oocytes of all the initial stock
Fertilization in each cycle is less likely to happen after 35 years of age. In addition, changes in the oocytes themselves occur with the age, leading to a possible genetic damage, and therefore the probability of having a child with genetic disorders increases.
Today many women put off motherhood until "better times" due to the modern pace of life, the economic situation, career development, and sometimes medical indications. When that time comes, it happens the women meet a problem to get pregnancy, even using IVF. Of course, the alternative would be the use of donor oocytes from young donors, but many still prefer to have a genetic own child. Until recently, it was an unsolvable problem.
In usual cryopreservation, oocytes were destroyed and only a new vitrification technology allowed freezing, defrosting, and, if necessary, refreezing them again successfully. So what is vitrification? This procedure of rapid freezing, when oocyte of the body temperature is placed in the cryoprotective medium of high concentrations directly exposed to liquid Nitrogen. Such rapid freezing prevents the formation of ice crystals within the cell, which would destroy it. The frozen oocytes may thus be stored for decades. The age and quality of the eggs remain the same as they were at the moment of puncture.
This procedure has enabled many women to give birth to their own healthy children even after undergoing chemotherapy and radiation therapy due to cancer.
Is there some kind of maternal risks associated with this procedure? As with any IVF procedure, there are minor risks associated with stimulation of superovulation and puncture of the ovaries. However, the risks could be minimized due to modern stimulation protocols and puncture under ultrasound control.
Evidence from all over the world demonstrates no difference in children’s health born after oocyte vitrification and fresh cycles.