The process of egg freezing

    Are you curious to know the process and timeframe of egg freezing? Here we guide you, step by step, on what to expect from the process of egg freezing at Cryos. 


    When doing egg freezing, we retrieve eggs from your ovaries and freeze them (also called cryopreservation). Cryopreserved eggs can be stored so you can use them for later fertility treatment when you would like to become pregnant. 

    Obviously, the more eggs you have in storage, the more possibilities you have of future pregnancies. That is why the first part of the process is to help your ovaries produce more eggs than usual, help them mature, and to prevent premature ovulation. After that, the actual egg retrieval will be performed, and finally the eggs will be frozen and stored.

    Employee at Cryos explaining the process of egg freezing step-by-step to young woman

    Egg freezing – step-by-step

    When you have decided to go ahead with the egg freezing, we are here to help you all the way from the initial contact and until your eggs are frozen and stored at Cryos or delivered to a Fertility Clinic of your choice.  

    The complete egg freezing process takes up to 8 weeks and includes the following steps:

    Step 1: Ovarian suppression 
    Ovarian suppression means to turn off your natural hormones temporarily by using birth control pills. Normally, your ovaries will release just one egg per month, but when doing egg freezing, we want to stimulate your body to produce more eggs. With ovarian suppression, we increase the effect of the hormone therapy that will help your body produce more eggs prior to the egg retrieval. 

    This step lasts for 2-4 weeks. In urgent cases, e.g., prior to medical treatment, this step may be skipped.

    Step 2: Ovarian stimulation 
    When your natural hormones have been temporarily turned off, you will begin the hormone therapy at home. This means that you must inject yourself with hormones that will stimulate your ovaries and help develop multiple mature eggs in both ovaries. This is the same process as if you would undergo IVF treatment (in-vitro fertilization).  

    This part of the process lasts between 10-14 days. During this period, you will need to make 4-6 visits to Cryos Egg Bank for ultrasounds and bloodwork, so we can monitor your progress.

    Step 3: Ovulation induction 
    When the ovarian follicles have reached appropriate maturity, we will trigger your ovulation with a specific medication. At this point, timing is vital for the success of the egg retrieval.

    Step 4: Egg retrieval 
    Now it is time for the actual egg retrieval. This will be performed 35-36 hours after ovulation induction. Egg retrieval means that your eggs are retrieved from the ovarian follicles with a needle. Our highly skilled staff will use an ultrasound device to guide the procedure, and you will be under intravenous sedation (IV). Egg retrieval is generally painless, but some women might be a little sore after the procedure and may experience some bloating. 

    Step 5: Egg vitrification  
    After the retrieval, we will evaluate the eggs to ensure that only mature eggs are frozen. Because more eggs are developed during the stimulation process than would be during a regular cycle, some of your retrieved eggs will not be mature and are therefore unsuitable for freezing. This is normal and expected. The actual egg freezing of the mature eggs will then be performed by our experienced embryologists in a process called vitrification

    Vitrification means that the liquid in the egg is removed and replaced with a cryoprotectant. Once the egg is loaded with cryoprotectant it is submerged in liquid nitrogen (-196°C) and the egg is “flash frozen”.  

    Woman having ultrasound during egg freezing process

    What happens to the eggs after the freezing?

    Once your eggs are frozen, we store them in our storage tanks. You can then keep them in storage here at our facilities or transfer them to your fertility clinic for fertility treatment. The frozen eggs can be stored indefinitely, and live births have been reported using eggs that were frozen over ten years ago. However, according to the law in Cyprus, women can store their eggs for a maximum of 10 years. This period may be extended by applying for a state approval. 

    Once you are ready to attempt pregnancy (this can be several years after the egg freezing), the eggs are thawed, injected with a single sperm to achieve fertilization, and transferred into your uterus as embryos. This procedure can be done at a fertility clinic of your choice. 

    How many eggs should I expect to freeze?  

    The number of eggs you should store depends on your plans and your age at the time of retrieval. We recommend a minimum of 10-15 frozen eggs for each IVF cycle or pregnancy attempt you want to plan. This number is based on existing studies, calculating average egg thaw and fertilization rates. Most women who are 35 years old or younger can expect to successfully freeze around 10-20 eggs per cycle. For some women 2-3 cycles of egg freezing maybe needed in order to preserve sufficient number of eggs.  

    Daughter hugging mother who is pregnant after fertility treatment with frozen eggs

    What are the pregnancy rates when using frozen eggs?

    Pregnancy rates from frozen eggs depend on the woman’s age at the time of the egg freezing process. The chance of pregnancy with eggs from women older than 38 at the time of freezing is likely to be lower than that seen for women in their 20’s and early 30’s. Cryos do not offer egg freezing to women who are 40 years old or more. 

    Are there any risks to children born from frozen eggs?

    According to the Female Fertility Preservation Guideline of ESHRE, current studies and observational data indicate that children conceived using frozen eggs do not have an increased risk of congenital anomalies. It is also mentioned that long-term cryopreservation (egg freezing) does not increase embryonic aneuploidy when compared to fresh eggs.

    In 2014 a study was done comparing outcomes from 1,224 fresh IVF cycles and 1,027 frozen egg cycles. In this study, zero differences were found in the rate of obstetric problems including diabetes, pregnancy induced hypertension, preterm birth and anaemia. Additionally, there were no differences in the gestational age at birth, birth weight, Apgar scores, birth defects, admission to neonatal ICU, perinatal mortality, or puerperal problems. Similarly, hundreds of thousands of children have been born from frozen embryos with no increase in birth defects.