Egg freezing
Women affected by, for example, cancer and women who are in a social situation where pregnancy is not desired at the time have a chance to preserve fertility. In 2011, Nordic IVF was the first clinic in the Nordic countries to offer freezing of unfertilized eggs for later use, so-called egg freezing or oocyte freezing.
Unfertilized egg cell freezing can be useful for a variety of reasons, including medical treatment that may harm ovarian function or if the woman is in a social situation where pregnancy is not desired. A later attempt to get pregnant with frozen eggs requires in vitro fertilization (IVF) and can be seen as an alternative to fertilization with donated eggs. Studies show that the possibility of pregnancy is as great as with traditional IVF with fresh eggs.
The technique
The vitrification technique was developed in Japan and the new freezing technique means that the eggs are frozen very quickly in a minimal volume of freezing solution, so-called vitrification. The eggs are then stored in special containers at -196 °C. Egg freezing preserves the quality of the eggs for several years, until the woman decides to use them in attempts to get pregnant.
Investigation before egg freezing
On your first visit, you will meet with a doctor for basic information and will be examined. The purpose of the investigation is to assess your possibilities for treatment and cryopreservation of unfertilized eggs. The investigation includes examinations such as a gynecological ultrasound examination and blood sampling for egg reserve (Anti Müllerian Hormone, AMH). When booking a doctor’s appointment, a health declaration is sent home to you. It is important that you fill out and bring the health declaration to the first visit so that you and the doctor can review it together.
All women undergo an infection screening for hepatitis and HIV, which is valid for a maximum of one year. After the ultrasound and blood tests, you meet the doctor for information and a summary.
How does the treatment work?
The treatment is carried out in the same way as hormone stimulation before regular IVF. In order to be able to freeze a proper number of eggs, the woman must undergo hormone stimulation, which is given as daily injections and causes the ovaries to mature several eggs at the same time. About 10 follicles per stimulation is a reasonable number. Such hormone treatment is usually started in connection with a menstrual period and lasts for about 10 days. The natural hormone secretion that controls the function of the ovaries is blocked at the same time by an anti-hormone (so-called antagonist), which prevents premature ovulation. The effectiveness of the treatment is monitored using ultrasound and, in some cases, blood tests. When the follicles are sufficiently large, a hormone injection is given to cause the egg cells to mature at the same time. The eggs are retrieved from the follicles by ultrasound-guided puncture and quickly taken care of by the laboratory staff for preparation and freezing.
The possibility of getting pregnant
Studies show that cryopreserved oocytes that are fertilized later after thawing have as good a chance of leading to pregnancy as fresh eggs. This means that women who need or want to postpone childbearing can be offered the opportunity to freeze eggs at a relatively young age in order to later have the opportunity to put back fertilized “young” eggs at an older age.
It is important to point out that although “young” eggs are preserved at egg freezing, the conditions for pregnancy for the individual woman can change due to higher age and other conditions. You can never guarantee that egg freezing will lead to pregnancy, but the possibility of pregnancy is preserved.
Eggs retrieved at an advanced age are of lower quality, which means a lower chance of pregnancy, an increased incidence of miscarriage, and an increased risk of chromosomal lesions in the fetus.