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Social Freezing

Precautionary freezing of ova for a later pregnancy

Ever since Apple and facebook have started offering their female employees in America to reimburse the costs of freezing their egg cells so that they can build a career before having children, the subject has been on everyone's lips. According to a survey* by the weekly "Die Zeit", many young women in Germany also think that preserving fertility by social freezing is sensible: more than half the females aged 14 to 29 and 40 to 49 could imagine deliberately postponing their pregnancy to a later date by this procedure, thereby considerably extending their reproductive life phase. But most of them reject the idea of having this funded by their employer.

Fertilization and pregnancy long after the collection of egg cells

The term 'social freezing' refers to the precautionary freezing (cryopreservation) of unfertilized but viable egg cells (metaphase II) after previous ovarian hyperstimulation. The reason for this is generally not a medical indication, as is already the case before tumour treatments (medical freezing), for example, but rather the wish for greater freedom in timing a possible pregnancy. This approach can also make sense if the ovarian reserve (POF/"primary ovarian failure") is already limited to start with, or in the presence of a condition that could impair it (ovarian endometriosis). The egg cells will then only be unfrozen, artificially inseminated (IVF/ICSI) and, after successful transfer of the embryo, carried to term by their donor at a time when the professional or private developments permit this and the couple has decided to have a child together. It is generally advisable to aim for pregnancy before reaching the age of 45. And given that pregnancy after the age of 50 is linked with significant age-related health risks for mother and child, there is a general understanding around the world that it should not be aimed for from this point in time at the latest.

Cryopreservation is a safe procedure

The method of cryopreserving cells has grown into an indispensable and safe procedure in reproductive medicine of late. We will for example freeze spare fertilized egg cells (pronuclear stage) in the course of an IVF or IVF/ICSI treatment to avoid health risks for the patient (hyperstimulation syndrome), or to be able to repeat the embryo transfer at a later date if no pregnancy has occurred. This allows a pregnancy to come about without the patient needing to undergo all the treatment's processes of stimulating the ovaries and puncturing the follicles again. In addition, cryopreservation also serves as a fertility protection measure before chemotherapy, with either mature egg cells and ovarian tissue being frozen, or sperm and testicular tissue.

The younger the woman, the better the quality of her egg cells

The ovarian reserve of a woman is the provided pool of ova able to develop into mature egg cells. As a woman grows older, her egg cells will not only become fewer, but their quality will also deteriorate: egg maturation (meiosis) will be attended by variable chromosomal aberrations, for example changes of the genome. This reduces the likelihood of a pregnancy as age increases. Women opting for the treatment in hand should therefore not be older than 37 years. Although cryopreservation is also still possible thereafter, the outlook for a successful treatment is markedly reduced. To enable the quality of the ova to be maintained, we apply the procedure of "rapid freezing" (vitrification) using a special medium. This involves the egg cells being dehydrated and cooled down to -196°C in liquid nitrogen within fractions of a second. As soon as the time for fertilization by microinsemination (IVF/ICSI) has come, we will unfreeze them just as quickly. With this process, around 90% of the cryopreserved oocytes will survive on average. While the freezing and unfreezing take place under very time-critical conditions, the storage could theoretically continue forever.

Success chances of IVF/ICSI after cryopreservation

Experience has shown that one or two out of ten fertilized egg cells will on average develop into vital embryos that are suitable for transfer to the uterus. Cryopreserved ova exhibit the same capacity to be fertilized and develop as fresh ones. And they also lead to pregnancy to the same extent, which most of all depends on the age of the patient and the number of fertilized oocytes. The number of mature and viable egg cells declines with advancing age. This means that several punctures and successive treatment procedures (IVF/ICSI) may be required to achieve an acceptable cumulative birth rate (>80%), depending on the age. A Belgian working group has for example found that ca. 23 mature egg cells need to be cryopreserved to achieve this objective before the age of 37, and ca. 56 mature ova on average thereafter, see Stoop, D., 2012**.

Costs and approach

Social freezing is an elaborate process that requires special expertise and an expensive infrastructure. All this is also linked with very considerable costs. If a cumulative birth rate of over 80% is to be achieved later on, a woman aged up to 30, for example, will require two puncture cycles and two treatment cycles (IVF/ICSI) on average. These costs are not covered by the statutory health insurance companies. Costs primarily incur only for the puncture cycles, the freezing and the annual storage. But the amount of the expenses depend basically on the individual ovarian reactivity (number of egg cells) and the age of the patient.

Social freezing is a procedure which may present an adequate alternative in specific cases. These also include an individually contingent early diminishment of the ovarian reserve. It is therefore meaningful for every young woman who wants to have children later to seek advice about her respective fertility outlook early on. This can lead to various different, staggered procedures from one case to the next. In some of them, preserving fertility by freezing ova can be the method of choice. Young women are already being provided with "assisted fertility counselling" in a number of countries to enable individual forecasts for this very reason. Extensive personalized fertility counselling also needs to precede any potential social freezing, in order to be able to explore the meaningfulness of this measure or its alternatives. We consider the provision of this counselling an essential task of the physician.

If you would like to seek your very own, personal advice on the subject of social freezing, please give us a call at +49 (0)221-27 76-200, send us an email, or use our form – we would be delighted to arrange an appointment with you!

*Die Zeit, no. 44/2014 dated 23/10/2014
**Stoop, D., Facts View Vis ObGyn, 2012