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Egg freezing – Information for patients

Patient information A-Z

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Five photos of embryos under a microscope and a photo of a baby

What is Egg Freezing?

At Cambridge IVF we can freeze your eggs and store them for you until you are ready to use them to have a baby.

Who is Egg Freezing for?

Premature infertility: You may wish to freeze your eggs if there is a risk you may become prematurely infertile. This may occur if you have been diagnosed with early menopause or if you are undergoing chemotherapy for the treatment of cancer.

Social egg freezing: The term ‘social egg freezing’ is used to describe women who wish to delay having a baby until later in life. Many women delay having a baby due to lifestyle factors such as career, financial stability and relationship status. Egg freezing means a woman can freeze her eggs at the optimal fertile age (ideally 35 or younger) and use these ‘younger’ eggs in fertility treatment at the time she chooses. Using younger eggs in fertility treatment has been demonstrated to result in a higher chance of achieving a pregnancy.

How Does the Process Work?

Consent: Before we can collect and freeze your eggs we need your consent. This is a legal requirement and we will ask you to consider and complete a series of electronic consent forms before you commence treatment.

There are 4 key areas we need to consider when we take legal consent to the storage of your eggs, these are:

  1. What should happen to the stored eggs in the event of your death or mental incapacitation. It is important that we know your wishes before we store your eggs. It may be possible to hand over the ownership of your eggs to a named person in your consent form, but all of these implications must be discussed with you at the time of consent.
  2. How long you wish to consent for your eggs to be stored. The statutory storage period for which eggs can be frozen is up to 10 years. You can of course decide to freeze them for a shorter period. You can also at any time prior to the eggs being used decide that you no longer want them to be kept in storage – for more information on the implications of this, please see our patient information on ‘Consent to treatment’ in particular the section on ‘Withdrawing, varying and restricting consent’.

In certain circumstances, the law allows eggs to be stored for up to 55 years. For this to be applicable, a registered medical practitioner will need to certify in writing that the patient is prematurely infertile or likely to become prematurely infertile. This written opinion will need to be renewed at least every 10 years during the 55-year storage period. We believe that the majority of patients are unlikely to need to freeze their eggs for longer than 10 years. However, if you think your situation is such that this is applicable to you, then our medical staff will be happy to discuss this with you.

  1. The law does not allow us to keep your eggs in storage beyond the date you have consented to. We will be in touch with you a few months before the end of the storage period to find out what you wish us to do. It is important that you keep in touch with us, in particular that you notify us of any change of address. If the storage limit is up, and you have not consented to extending this limit, we are obliged by law to let any stored eggs perish, even if we have not been able to trace you first.
  2. If you wish you can consent to the use of your eggs in research or donate them for the use of other people for their treatment if you decide that you do not need the eggs for your own use anymore.

It is important that you answer these questions as clearly as you can leaving nothing open to interpretation as your wishes on these issues are required by law before we freeze your eggs.

Build up work

What types of screening are required?

The following tests are required for all women considering egg freezing. In some cases, additional tests may be required, which will be discussed with you by our team.

BMI (body mass index)

Ideally, your BMI (the ratio of your weight in kilograms to the square of your height in metres) should be in the normal range, between 19 and 25. We do not accept anyone whose BMI is greater than 35 for treatment. Having a normal BMI enhances the chances of successful outcome of treatment and decreases risks of complications.

Chlamydia infection

All patients embarking on fertility treatment are routinely screened for Chlamydia infection. Your GP will have been asked to perform this screening prior to referral. If this has not been the case, swabs will be taken prior to commencing treatment. The test should have been done within 1 year of starting treatment.

Cervical smear

You need to be up to date with cervical smears. If you are unsure when you were last tested, please contact your GP and arrange a repeat smear if necessary.

Tests for hepatitis and HIV

Screening for Hepatitis B and C and HIV is a pre-requisite for all patients entering the egg freezing programme. Pre-test counselling will be offered if you wish to discuss the implication of these tests. The results of these tests may affect your care pathway and counselling will be available if any result is positive. Tests should have been done within 3 months of starting treatment. The tests are performed to allow us to store your eggs appropriately in a screened or viral positive storage facility. Tests may be funded by the NHS or in some cases you may have to pay for them. The cost for the tests in such circumstances is available in the Cambridge IVF schedule of fees.

FSH level

FSH, or Follicle Stimulating Hormone, is produced by the pituitary gland and regulates the functioning of the ovaries. A test for FSH level is carried out between days 1 and 2 of your menstrual cycle. High levels of FSH may reflect a reduced ovarian reserve, which reduces the chances of success with egg recruitment. The test is recommended to help prognosticate regarding the outcome of treatment.


AMH or Anti–Mullerian Hormone is produced by the ovaries. This is also used as a marker for ovarian reserve. The clinical team will advise you regarding this test and the advantage it offers over FSH. If you need more information regarding this test, please ask for an AMH patient leaflet.

What are the requirements for the ‘welfare of the child’ assessment?

Fertility treatment in the UK is governed by the Human Fertilisation and Embryology Act of 2008, which places a duty on clinics providing treatment to consider the welfare of any child who may be born as a result of treatment. According to guidance issued by the regulator, clinics have to take into account the need for supportive parenting and factors which are likely to cause serious physical, psychological or medical harm to the child to be born or to any existing child of the family. Each patient requesting treatment must complete a form which includes questions dealing with such issues.

We will then consider your responses and, in some cases, may need to seek further information, for instance from your doctor, social services or other professionals. If, after deliberation we decide that we are not able to offer you treatment, we will give you our grounds for making the decision. We will also outline what steps, if any, you could take for us to reconsider our decision.

Treatment cycle

Normally a woman only produces one mature egg every month. Ovarian stimulation leads to the production of multiple eggs (average of 8-12), which are collected from the ovaries and frozen for future use.

Drugs used in a stimulation phase are as follows:

  • Daily injections to stimulate the ovaries to produce more than one egg
  • A second injection is added on day 4-5 of stimulation to prevent spontaneous premature release of eggs
  • A single injection which is carefully timed to begin the process of ovulation followed by egg collection

The stimulation phase of your treatment cycle is monitored by regular blood tests and ultrasound scans.

Egg collection

Your eggs will be collected in the morning on a Monday, Wednesday or Friday. Before the procedure begins a small needle will be used to introduce a plastic tube into a vein in your hand or arm. We will give you some medication through the tube, which will make you drowsy and relaxed during the egg collection. You will not be asleep but you may not remember the procedure.

Your legs will then be put into special supports and you will have an internal examination and scan. A fine needle is inserted through your vagina and into the ovary. This is connected to a vacuum pump, which allows us to drain the fluid from each follicle into test tubes. These test tubes are passed to the embryologist in the adjoining laboratory who will identify the eggs and place them in a dish of culture medium in an incubator compartment that is clearly labelled with your name using the RI witness system.

The procedure is repeated on both ovaries, until all follicles likely to contain eggs have been drained. The whole procedure lasts for around 30 minutes depending on how many follicles are present. We expect to obtain eggs from approximately 75% of mature follicles.

Egg freezing

All healthy looking mature eggs will be frozen around 2 hours after your egg collection. We use a process called vitrification to rapidly freeze your eggs which we then store in our cryostore for you to use in the future within the time period you have consented to.

Using your frozen eggs to have a baby

What is the likelihood the eggs will survive?

We expect 80% or more of the eggs to survive the freezing and thawing process. In rare cases, very few of the eggs or none of the eggs will survive. This is unpredictable and can be patient specific.

When happens after thawing?

After thawing we will need to ensure that the eggs meet the sperm in order to allow the process of fertilisation to take place and to allow subsequent embryos to develop. We will inseminate your eggs using a procedure called Intracytoplasmic-sperm-injection (ICSI). During ICSI we select a single sperm and manually inject it into the middle of the egg. Please be aware that ICSI treatment is recommended when using frozen-thawed eggs in treatment as opposed to conventional IVF. This is because studies have demonstrated that the shell surrounding the egg hardens during the freezing process and can therefore prevent the sperm from entering the egg. We can overcome this problem by using ICSI.

When the ICSI procedure is completed your cycle will follow the normal treatment pathway. Please see our ‘laboratory guide for patients’ for further information.

What is my chance of a successful outcome using frozen eggs?

Studies have demonstrated that your chance of a successful outcome using frozen-thawed eggs is the same as using fresh eggs in ICSI treatment. Of course, in your case, the biological age of your eggs will be younger than you at the time of treatment. This should increase your chance of a successful outcome compared to other women in your age group using their own fresh eggs.

What are the risks to a child born using frozen eggs?

There is no evidence that any babies resulting from thawed eggs have an increased risk of harm or abnormality or that the pregnancy itself is at more risk because a frozen / thawed egg has been used. Cambridge IVF constantly monitor our results and pass on information to the HFEA which allows high power data analysis to be carried out at a national level to ensure that we continue to operate safely and in as informed an environment as possible.

Could anything go wrong with our storage?

Cambridge IVF has a state of the art Cryostorage facility on site. Eggs are stored at very low (-196oC) temperatures using liquid nitrogen.

We do everything we can to maintain a high quality cryostore. We have a system in place that monitors the cryostore continually and will alert us immediately if there is the slightest suggestion of a problem. We use a high security storage system to reduce the theoretical risks of cross contamination between samples. Even with our exacting standards and commitment to quality in everything we do, we cannot provide a guarantee that your stored eggs may not be affected in the event of an ‘act of god’, civil disturbance, catastrophic equipment failure or any other unexpected and abnormal occurrence which may affect our service or facilities.

Staffing expertise

Our scientific team has been carefully put together with a collective experience of over 30 years in the profession spanning more than 10 well respected clinics across the UK and Europe.

Our embryologists are either registered with the Health and Care Professions Council (HCPC) or are working towards it and have all attained certification with the Association of Clinical Embryologists having successfully completed their internationally acclaimed training scheme.

We have put together the team based not only on the skill of the scientists and their depth of knowledge but also their desire to make Cambridge IVF a patient focused and friendly unit which not only excels clinically but achieves this whilst maintaining a close and open relationship with our patients.

Comment on witnessing

We are all very aware there have been IVF mix-ups in other clinics in the UK and across the world. Cambridge IVF has taken every step possible to minimise the risk of mix up occurring here. In addition to stringent checking and procedural controls being in place, we have invested in an electronic system called RI Witness which prevents the mixing of sperm and eggs from different patients or the transfer of the incorrect embryos in your cycle. We are not saying we are likely to have made a mistake without it, this could not be further from the truth but we do believe in making our processes as safe and risk free as possible and we believe that RI Witness ensures this.

We hope you have found this booklet informative and interesting. We realise we may not have covered all of your questions so if you do have any other queries we are here to help so please contact us via any of the means below:

Cambridge IVF
Kefford House
Maris Lane

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