introduction

The ability to freeze human oocytes, whether fertilized or unfertilized, gives women who do not want maternity at a young age more time flexibility in family planning. While the method of freezing has been used experimentally for decades, it is only through the recent development of a " flash freezing" method, that the rate of oocytes surviving the procedure of defrosting and defrosting has risen so far that a regular implementation of Krykonservierung is at least technically possible. However, since egg cell freezing also involves risks and costs that are not to be despised, but above all because it is a major interference with the process of human reproduction, the ethical and social aspects of this issue are controversial.

history

Originally, the procedure for freezing a human ovum as a variation of artificial insemination was developed to enable a later pregnancy to be provided to young women who were at risk of losing fertility as a result of cancer treatment by radiation or chemotherapy, The first successful onset of a previously cryopreserved oocyte occurred in 1986. Since a few years ago, the newly developed method of freezing was developed, the survival rate of a frozen egg is usually over 80%. A few years ago, the American Society for Reproductive Medicine stated that it no longer considered the process of freezing a human ovum as an experimental process.

Biological-technical background

To successfully store a human ovum for years or decades, and then use it to induce pregnancy, three hurdles have to be overcome.

First, a mature, healthy oocyte must be taken from the woman, or several to compensate for subsequent losses. As a guide size as required number about 10 to 20 are called. Three aspects in particular are problematic: in one healthy woman, usually only one egg ripens per month, whereby the quality of this egg cell decreases rapidly with increasing age of the woman. For removal an intervention under general anesthesia is necessary. In order to protect the woman from many procedures, she will be treated with hormone before surgery to increase the number of jumping eggs per period. As with a fertility or fertility treatment, the ovary is stimulated (stimulated). Typically, this hormone treatment is carried out with the drug clomiphene in tablet form or the hormones FSH / LH by syringe. This drastically reduces the number of removal procedures required so that now usually 2 to 3 removal procedures are sufficient to freeze more than 10 "good" egg cells for freezing. The problem remains, however, that the quality of the oocytes of a woman over the age of 25 steadily decreases. For example, less than 50% of oocytes are fertile for a 30-year-old, and less than 20% for a 40-year-old. Corresponding monthly chances of a naturally occurring pregnancy are about 20% for a 30-year-old woman and about 5% for a 40-year-old woman. A 25-year-old, however, who would be eligible for a removal at the optimal age, does not usually see the need for a Eizellvorsorge, nor would they have the necessary financial resources on hand. If the desired partner still can not be found beyond the 35 years, or if the professional career is currently more in the acute focus of interest, then the ticking of the biological clock makes the possibility of cryopreservation look much more seductive, especially as it ages a necessary financial leeway is given. As a result, the average woman wishing to freeze eggs will naturally have to undergo several cycles of hormonal treatments and removal procedures to achieve the required number of healthy oocytes due to naturally impaired fertility.

The second hurdle is technical. To enable a biological material to survive for years, without natural aging or decomposition by microorganisms causing an undesirable end to life, freezing is the means of choice. The problem: When ice crystals form, they break through the cell boundaries of the frozen biomaterial because they are sharp-edged. As a result, the cells are irreparably destroyed, thawing now presents only mud. In order to prevent the formation of crystals, sometimes antifreeze - so-called cryoprotectants - added and freezing is either (as formerly usual) very slowly, or very quickly (new method). As part of so-called vitrification, the cell material is cooled down to about -200 ° C in just over a second, preferably with the aid of liquid nitrogen. Disadvantage is that the use of some toxic antifreeze can not be prevented.

As a third hurdle presents itself after successful removal, selection, freezing, thawing and a (in comparison, at least technically rather unproblematic) artificial insemination, the task now to insert this egg into the uterus ( uterus ) of the woman. Since it is often, especially in older women - especially because of a reduced blood flow - does not come to a successful implantation, it is legally allowed in Germany, bring up to three fertilized eggs simultaneously. However, this also leads increasingly to multiple pregnancies. In order to increase the chances of implantation, additional previous hormone therapy may also be necessary. This can then provide a more pronounced mucous membrane of the uterus for a more favorable starting position.

Medical risks

For the child resulting from a frozen egg including artificial insemination, there are no known risks of hereditary diseases or other diseases beyond the average size; already thousands of children were conceived in this way. However, by the usually advanced age of the expectant mother, there is by definition a risk pregnancy with sometimes considerably increased probabilities for numerous pregnancy complications. The miscarriage risk is significantly increased.

In addition to the increased risks associated with a late pregnancy, the woman also directly exposes herself to an above-average risk to her health as a result of procedural interventions and hormone treatments. Nausea and vomiting are the most common undesirable effects that can occur during ovarian stimulation hormone therapy. However, a so-called ovarian hyperstimulation syndrome ( OHSS abbreviated) is less common. In this more serious complication, nausea and vomiting, and sometimes abdominal pain, are again expected in the mild, more usual form. About 1% of patients develop a worse form of ovarian hyperstimulation syndrome, which may be associated with blisters ( cysts ) on the ovaries, ascites, dyspnea, and coagulation disorders. Especially younger women and those with bladder-rich ovaries ( polycystic ovaries ) are at an increased risk of suffering from ovarian hyperstimulation syndrome through hormone treatment.

Ultimately, a decision for egg cell care should also take into account the risks that result from the oocyte withdrawal itself. Although this procedure is usually carried out under general anesthesia, it is not a complicated matter for the surgeon, but even if the risks for bleeding, infections etc., in addition to those of an anesthetic complication, are quite low, they can never be completely ruled out. A conscientious consideration of opportunities, costs and risks should therefore always precede a decision for such a procedure, which is not medically necessary.

costs

Usually, the costs of hormone treatments, removal procedures, egg storage, placement, etc., which are incurred in the context of a Eizellvorsorge, not covered by the health insurance. Should follow-up costs arise as a result of complications occurring as part of these medically unnecessary treatments, these must also be paid for privately.

In terms of their amount, the costs incurred are by no means insignificant, but the safekeeping of the eggs on a so-called cryobank costs hundreds of euros per year. Overall, of course, depending on the provider, number of necessary removal interventions, etc., usually costs in the high four-digit or even five-digit range can be expected.

Social implications

In the biologically optimal age for a pregnancy - between about 20 and 25 years - the average woman in a western industrialized nation is usually more in education or at the start of a career than in marital or illegitimate solid partnership, only in individual cases, it comes here to deliberate motherhood, The emancipated woman is expected to do the same to the man in education and career promotion ambitions. Also, the lack of large family associations and sufficient social and state support in child care in Germany a problem-free coexistence of family and work of both parents de facto is not given. Many couples decide only "at the last minute" for a then often numerically quite poor failing family.

By allowing an egg to freeze, the individual woman will undoubtedly have more room for maneuver in family planning, to the extent that it will then be possible to postpone the establishment or expansion of the family beyond the natural fertility phase. The problem is that by the existence of this possibility (especially in the case of assumption of costs, for example by the employer), the social expectations of women are made possible to actually take advantage of this option, for example, to devote themselves to a job in their "best" years and not the founding of a family. Whether the reconciliation of work and family with 40 or even 50 years is rather given, seems highly questionable. However, from a medical point of view, it is strictly forbidden to postpone starting a family until after retirement, ie retirement or retirement age. Even for the hurdles of raising and raising children, younger parents are generally better equipped than "fit" seniors.

To what extent the existence of the possibility of being able to freeze a human egg cell for the purpose of a postponed, artificial reproduction is ethically desirable, and to what extent the exercise of this option makes sense in society is an open question.

All in all, it can only be said that the process of cryopreservation has left the experimental stage medically and technically, although it is routinely possible, but not risk-free. Biologically, however, natural pregnancy at 20 to 25 years of age (except in exceptional cases, such as cancer) is always superior to delayed motherhood using reproductive medicine and is therefore preferable.

Illustration of an egg

Figure secondary follicles (A), indirect cell division (B) and internal female genitalia (C)
  1. Ground Skin -
    Membrane basalis folliculi
  2. nuclear layer
    (core-rich layer
    of follicular cells) -
    Epithelium stratificatum
    cuboideum
  3. Körnkörperchen -
    nucleolus
  4. Basic tissue of the ovary -
    Stroma ovarii
  5. Oocyte - Ovocytus
  6. Nuclear nucleus
  7. Glass Skin - Zona pellucida
  8. Uterus - uterus
  9. Vagina - vagina
  10. Ovary - ovary
  11. Fallopian tubes - tuba uterina
  12. polar body

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