Introduction
The possibility of freezing human oocytes, whether fertilized or unfertilized, gives women who do not wish to have a mother at a young age more time flexibility in family planning. While the freezing procedure has been used experimentally for decades, it is only with the recent development of a “shock freezing” method, known as flash freezing, that the rate of oocytes that survive the procedure of thawing and defrosting undamaged has increased to such an extent that regular cryopreservation is at least technically possible. However, since the freezing of oocytes is associated with risks and costs, and especially since it represents a significant intervention in the course of human reproduction, the ethical and social aspects of this topic are controversially discussed.
History
Originally, the procedure for freezing a human egg cell was developed as a variation on in vitro fertilization in order to enable young women who were likely to lose their fertility as a result of cancer treatment using radiation or chemotherapy to still be able to become pregnant at a later stage. The first successful implantation of a previously cryopreserved egg cell took place as early as 1986, and since the newly developed method of freezing was developed a few years ago, the survival rate of a frozen egg cell is usually over 80%. A few years ago, the American Society for Reproductive Medicine declared that it no longer considered the process of freezing a human egg cell an experimental process.
When does it make sense to freeze eggs at all?
Some diseases, especially cancer, can threaten fertility due to the subsequent therapy. These include not only some medications that damage germ cells, but also radiation in the area of the pelvis and thus the reproductive organs or certain operations can have a negative influence on fertility. Furthermore, in the case of a genetic predisposition to premature loss of ovarian function, freezing (cryopreservation) of eggs can also be useful. Common to all indications is that egg freezing is a preventive, i.e. prophylactic, procedure. Therefore, the functioning of the ovary at the time of egg retrieval and freezing is a prerequisite and should always take place before any probable damage to ovarian function occurs.
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