The conversation about future parenthood can begin long before the decision to become pregnant. Sometimes the reason is the wish to preserve eggs for a later stage in life. In other cases, treatment that may affect reproductive function is coming up, or embryos have already been obtained during an IVF procedure.
Modern reproductive medicine offers different approaches to these situations. Egg freezing and embryo freezing are two of them, and vitrification is the laboratory method by which they can be stored.
At Adella Clinic we start with a conversation about your health and plans, in order to explain what each approach could offer and what it involves in practice.
What is the difference between freezing eggs and embryos?
In egg freezing, mature, unfertilised female reproductive cells are stored. At this stage no semen sample is needed, and the decision on whose sperm will be used to fertilise them can be made later.
In embryo freezing, fertilisation has already taken place in the laboratory. The eggs are fertilised with sperm from a partner or donor, and the resulting embryos are stored for future transfer.
This difference matters both for medical planning and for personal choice. With eggs, fertilisation and assessment of embryo development are still ahead, whereas with embryos we already have information about these initial stages.
What is vitrification?
Vitrification is the method of extremely rapid cooling in which cells and the solution surrounding them turn into a glass-like state. Special protective solutions called cryoprotectants are used, which help prevent the formation of damaging ice crystals.
After processing, the eggs or embryos are placed in labelled carriers and stored at an ultra-low temperature, usually in liquid nitrogen at around minus 196°C. Identification and tracking of the material are part of laboratory control throughout the storage period.
The method allows egg retrieval or embryo creation to be separated in time from the subsequent attempt at pregnancy.
When is egg freezing discussed?
Planned egg storage can be discussed when pregnancy is not part of your current plans, but you want to explore the options for future parenthood. In international practice the term “social freezing” is also used for this choice.
Medical reasons can also lead to such a consultation. These include upcoming chemotherapy, certain types of radiotherapy or surgery that may affect ovarian function. In the case of cancer, the reproductive specialist coordinates the approach with the treating team, so that fertility preservation is aligned with the necessary main treatment.
Egg freezing: procedure and preparation
Before proceeding with egg freezing, we assess your medical history and ovarian reserve. Testing anti-Müllerian hormone, known as AMH, and the ultrasound count of antral follicles help us estimate the expected response to stimulation. Antral follicles are small structures in the ovaries that can be seen on an ultrasound scan.
These markers mainly provide information about the likely number of eggs. They do not directly measure egg quality and cannot on their own predict a future pregnancy.
This is followed by medication-based stimulation, which usually lasts about 10 to 14 days. During this period we monitor follicle development with ultrasound scans and, if necessary, hormone tests. When they reach a suitable stage, medication is given for the final maturation of the eggs.
The eggs are retrieved by follicle aspiration under ultrasound guidance, usually with short intravenous anaesthesia. The embryologist assesses the eggs retrieved, and the mature ones are prepared for vitrification.
After a short period of observation you can usually go home the same day. Bloating, tension and mild discomfort are possible. We also discuss in advance the rarer complications, including an excessive ovarian response to stimulation, as well as the recovery instructions.
When do we freeze embryos?
During IVF treatment, more suitable embryos may be obtained than will be used for the immediate transfer. Storing them makes it possible to plan another transfer, including for another pregnancy, without repeating stimulation and egg retrieval to obtain these embryos.
In other cases, the medical team may recommend freezing the embryos and postponing the transfer to a later cycle. This is done, for example, for certain patients at increased risk of ovarian hyperstimulation syndrome.
The decision on when to perform the transfer is part of the treatment plan. It takes into account the woman's condition, how the stimulation went and the conditions for the uterine lining to receive the embryo.
How are stored eggs and embryos used?
When you decide to use your frozen eggs, your current state of health is assessed first. After thawing, the preserved eggs are usually fertilised by ICSI, a method in which the embryologist injects a single sperm into the egg. The resulting embryos are monitored in the laboratory and a transfer is planned.
With stored embryos, fertilisation has already taken place. Preparation focuses on the uterine lining, called the endometrium, and on correctly determining the timing of the transfer. This can be done in a natural cycle with ovulation monitoring or with medication-based preparation.
What are realistic expectations?
The age at which eggs are retrieved matters for their reproductive potential. Vitrification is used to preserve them, but it does not improve their original quality. For a future pregnancy, the woman's health and age at that time are assessed separately.
It is also important to distinguish between cells surviving thawing and the likelihood of having a baby. After thawing, eggs still need to be fertilised, develop into embryos and be transferred, and for embryos their subsequent implantation in the uterus also matters.
That is why freezing creates an additional option for future treatment, without guaranteeing a specific result. General success rate data serve as a guide, while a personal prognosis requires a more detailed assessment.
Talking about your plans
At Adella Clinic we will discuss what can be expected from the procedure in your case, which visits are needed and what the costs of preparation, freezing, storage and subsequent use include.
You can also seek a consultation while you are still considering your options. The purpose of this meeting is for you to receive clear information and answers to your questions, so that you can make a decision that suits your circumstances and wishes.
Frequently asked questions
Is one egg freezing procedure enough?
For some women one cycle provides a suitable number of mature eggs, while for others additional stimulation may be discussed. This depends on the ovarian response and reproductive plans. There is no universal number of eggs that guarantees a future birth.
Is a frozen embryo transfer more successful than a fresh transfer?
Neither approach has an advantage in all cases. Postponing the transfer may improve safety in certain medical circumstances, but it does not automatically increase the chance of pregnancy for every patient.
What is important to clarify about storage?
Before the procedure we discuss the storage period and conditions, the necessary documents and how subsequent use is requested. It is also good to be clear about the periodic fees and whom to contact if your plans change.
