Egg freezing… For some women suffering from chronic or serious illnesses, this technique of medically assisted procreation is sometimes the only recourse to preserve their fertility and hope to see their childbearing plan one day come true. But oocyte cryopreservation also has other indications that are often less well known. Overview of this practice in France.

Freezing oocytes, also known as oocyte cryopreservation, is a method of preserving fertility. It consists in taking the oocytes, after ovarian stimulation or not, before freezing them in liquid nitrogen and storing them for a subsequent pregnancy.

In France, oocyte cryopreservation is regulated by law and more particularly article L-2141-11 of the Health Code, like all fertility preservation treatments (embryonic or sperm freezing, preservation of ovarian tissue or testicular tissue). This text stipulates that “any person whose medical care is likely to impair fertility, or whose fertility risks being prematurely impaired, can benefit from the collection and conservation of their gametes […] with a view to subsequent provision, for his benefit, of medically assisted procreation, or with a view to preserving and restoring his fertility. “

This is therefore the primary indication for the freezing of the oocyte: to allow women to preserve their fertility when taking a heavy treatment can potentially damage their ovarian reserve. Oocyte cryopreservation is therefore most commonly intended for women having to undergo chemotherapy (in particular those associated with a bone marrow transplant) or radiotherapy, especially in the pelvic region.

Ninu ibeere:

• These treatments are highly toxic to the ovaries (they are said to be gonadotoxic), primitive cells (immature oocytes) and ovarian function;
• They also generally require patients to put off their childbearing plans for a long time, sometimes by several years, the time to carry out the treatment and to ensure the necessary follow-up for gestation.

But cancers are not the only diseases for which fertility preservation can be proposed. Thus, freezing the oocyte may be recommended in the event of:

• taking another gonadotoxic treatment. This is the case, for example, in the management of organ transplants or diseases of the immune system (immunosuppressive drugs) or in certain hematological diseases such as sickle cell anemia;
• surgery that can affect fertility;
• congenital ovarian disease. Often genetic, these diseases, such as Turner syndrome, can lead to premature ovarian failure.

Note: in the event of illness, freezing the eggs is especially recommended in pubescent women, generally under 37 years of age. On the other hand, if preservation of fertility is indicated in a little girl or prepubertal adolescent, recourse to preservation of the ovarian tissue may be favored with a view to performing an autograft of these tissues later.

Far from these cases specifically linked to a disease, there is another indication for the freezing of oocytes: the gender transition.

Indeed, during a gender transition process, the recommended medical or surgical treatments can also damage fertility. Thus, if you are starting a masculinizing journey, you may be advised to store and therefore freeze your oocytes. There remains today a great unknown: the use of these frozen gametes within the framework of a MAP (medically assisted procreation), which is still limited by the law of Bioethics in force since 2011. The evolution of the legislation could however facilitate access to parenthood for these patients.

A couple already enrolled in a MAP course for infertility may also have to resort to oocyte cryopreservation if:

• the puncture makes it possible to obtain supernumerary oocytes which cannot be fertilized;
• sperm collection fails on the day of in vitro fertilization. The objective is then simple: to avoid “losing” the gametes removed and to keep them until the next attempt at IVF.

Many European countries now authorize the freezing of so-called “comfort” oocytes in order to allow women to keep their gametes for a subsequent pregnancy without medical indication. The objective is therefore essentially to be able to push back the age of motherhood without suffering the decline in fertility linked to the advancing age.

In France, the freezing of comfort oocytes (also called self-preservation of oocytes) is currently only authorized in one case: oocyte donation. Initially reserved for adult women who have already had a child, this donation has evolved with the Bioethics law of July 7, 2011. The novelty of this text: nulliparas (women who have not had children) are now entitled to donate their children. oocytes and allowed to keep some of them in anticipation of a subsequent pregnancy.

This freezing of oocytes without medical indication remains, however, very limited:

• The donor must be informed in advance of her subsequent chances of pregnancy from the oocytes that she has been able to keep;
• It undertakes that half of the oocytes collected will be dedicated to donation on a basis of at least 5 oocytes (if 5 oocytes or less are taken, all go to donation and no freezing is possible for the donor);
• The donor can only make two donations.

The fact remains that the reform of oocyte donation opens a de facto right to self-preservation which continues to be debated: should it be opened to all women outside of donation, given the progress of age of maternity? Here again, the revision of the Bioethics law could soon provide a legal answer to this questioning. In the meantime, learned societies and the Academy of Medicine in particular have come out in favor.

The freezing of oocytes today is essentially based on a technique: oocyte vitrification. The principle ? The oocytes are immersed directly in liquid nitrogen where they are frozen ultra-quickly at a temperature of -196 ° C. More effective than the technique of slow freezing previously used, vitrification makes it possible to ensure better survival of frozen oocytes, in particular by preventing the formation of crystals which previously altered the gametes, rendering them unusable.

To be possible, the freezing of the oocyte is part of a treatment protocol. This varies depending on the urgency of the treatment and the disease in question. If you are concerned you will, in all cases, have to have an initial consultation with your doctor who will explain to you:

• the toxicity of the treatment;
• the fertility preservation solutions available to you;
• the chances of pregnancy (which is never guaranteed) and possible alternatives;
• the contraception to be put in place while waiting for the start of treatment.

He will then ask you to make an appointment for a multidisciplinary consultation to preserve fertility, which will determine the conditions for your treatment. Two options are then possible:

• If you are of childbearing age, have no contraindication to hormonal treatment and your treatment (chemotherapy, radiotherapy, etc.) is not very urgent, your treatment will begin with stimulation ovarian to promote the arrival at maturity of a maximum of oocytes. In this context, you will benefit from the “classic” follow-up of in vitro fertilization: stimulation, ultrasound and biological follow-up, triggering of ovulation and oocyte puncture;
• If you cannot have stimulation (your treatment is urgent, you have hormone-dependent cancer such as breast cancer), your doctor will usually recommend a vitrification protocol without stimulation. What does it consist on ? After a puncture of immature oocytes, the gametes are cultured in the laboratory for 24 to 48 hours to reach maturity. This is called in vitro maturation (IVM).

The mature oocytes thus obtained (by stimulation or by IVM) are then frozen before being used subsequently in the context of medically assisted procreation. Note: in some cases, the practitioner may recommend in vitro fertilization prior to freezing. Do not hesitate to discuss the matter with your doctor.

While the chances of getting pregnant after egg freezing have increased thanks to technical advances like vitrification, it’s important to keep in mind that getting pregnant is never guaranteed.

Some figures attest to this, compiled by the Academy of Medicine:

• During a vitrification procedure, between 8 and 13 oocytes are collected on average per cycle;
• After thawing, 85% of these same oocytes survive;
• Then, IVF by ICSI, which makes it possible to fertilize the remaining oocytes, has a success rate of 70%.

Result: the overall pregnancy rate with thawing of oocytes fluctuates between 4,5 and 12% depending on age and health conditions. It is therefore estimated that it is necessary to successfully freeze between 15 and 20 oocytes to hope to have a birth. This generally implies several collections and several freezes to finally hope to be parents.