Egg freezing

Egg freezing

Egg freezing

Egg freezing

The Lister Fertility Clinic offers egg freezing with successful pregnancy outcomes following the freeze / thaw process. As later success with frozen eggs is dependant on the number frozen, we are now offering 3-cycle packages.

Over the last 30 years the average age of women in their first pregnancy in the UK has consistently increased and as of 2013 is over 30 for the first time and over 20% of babies are now born to mothers over 35.

These changes, although now a socially driven way of life can prove counterproductive from a purely reproductive perspective. “Social” egg freezing allows women the option of freezing their eggs when younger. This may offer her a better chance of a successful pregnancy in the future than using her older “fresh” eggs, which may be lower in both quality and quantity.

The introduction of “vitrification”, a new rapid cryopreservation technique that minimises crystal formation and therefore limits damage during the freeze/thaw process has made egg freezing as a means to potentially preserve a woman’s long-term fertility a viable option.

Although, many thousands of eggs have safely been stored in the UK since 2001, the number of babies born from thawed eggs remains low in comparison. Initially, older less effective freezing techniques were utilised and many of the women who have undertaken egg freezing for social reasons have yet to use their eggs or didn’t need to as they conceived naturally later in life.

What is the success rate of frozen thawed eggs?

Increasing worldwide data is suggesting that frozen eggs may be as effective in achieving pregnancy as fresh eggs and long term data on pregnancy risks such as preterm labour or birth defects shows no increase. The confidence in the success of frozen eggs is such that, in some clinics, frozen eggs are preferentiallly being offered to women requiring egg donation.

Since adoption of the vitrification technique* in October 2009 we have performed over 1000 cycles of social egg freezing at the Lister.

The table below outlines our success with the thaw cycles (to Dec 2018) using eggs following a planned egg freeze utilising this validated technique and the most recent national data which at the moment does not make a distinction between slow-frozen eggs and vitrified eggs.

Lister Vitrification DataMost recent HFEA Data
Egg Survival Rate72.3%62.3%
Pregnancy Rate / Thaw cycle43.8% (21/48)
Ongoing Pregnancy Rate / Thaw cycle31.5% (23/73)13.9%
Pregnancy Rate / Embryo Transfer53.3% (21/36)22.2%
Ongoing Pregnancy Rate / Embryo Transfer44.2% (23/52)


How many eggs should I aim to freeze?

To maximise the chances of conception following egg freezing, a number of stimulation cycles may be required. From our egg thaw cycles themselves (up to Dec 2018) 1 in every 19 eggs thawed has achieved a pregnancy and 1 in 22 a livebirth/ongoing pregnancy.

Dividing by age, 1 in 15 eggs frozen <35 have achieved a livebirth/ongoing pregnancy, 1 in 23 eggs frozen between 35 to 40 have achieved a livebirth/ongoing pregnancy and 1 in 35 eggs frozen over 40 have achieved a livebirth/ongoing pregnancy.

Clearly, the younger you are, the higher the chance that eggs will achieve success. We would therefore recommend women to freeze at as young an age as possible and aim for at least 20 eggs in storage. However, there is no guarantee of success with any number as other factors such as egg quality are also relevant. Some women may achieve a success with only a few eggs and some may be unsuccessful with over 20. We therefore offer egg freezing packages for those considering more than one stimulation cycle.

What is the ideal age to freeze your eggs?

The main benefit of freezing your eggs is that it “locks in” the quality of a woman’s eggs at the age they were frozen. These eggs can be used at a later stage when the quality of her own remaining eggs may be significantly reduced in comparison. So, the easy answer would be as early as possible but it is not as simple as that.

Despite the decline in both egg quality and quantity with age, there are pitfalls and risks to both freezing too early as well as too late and it is therefore a difficult balance between any social benefit and the physical, emotional and financial burden of treatment.

In theory the earlier a women freezes her eggs, the higher the quality and therefore potential future success with them. However, the earlier you freeze them, the less likely you will ever need to thaw and use them in the future as the chances of a natural pregnancy will be higher.

In contrast, waiting to your late 30s or early 40s would allow you more time to start a family naturally. Social trends have shown us that many women may not be ready to start a family at this age or may not have a relationship that they desire at this point and if this is the case, the expected success rate of eggs frozen at this point will be much lower.

Similarly from a social perspective, freezing your eggs may allow you the peace of mind of a potential “fertility insurance policy” for the future if ever needed but there is never any guarantee of success. Freezing should never be seen as a definitive alternative to natural conception as it is not. Such a feeling of false reassurance may be in fact detrimental to overall chances of conception.

So in summary, the longer you wait over time the declining egg quantity and quality will result in a lower chance of having a successful pregnancy.

So we would recommend consideration of egg freezing:

  • If embarking on any treatment (such as radiotherapy or chemotherapy) that may impact on ovarian reserve and future fertility
  • Ideally in your early to mid 30s if single and not planning to imminently start a family
  • In those over 35, depending on social circumstance and your egg reserve but the numbers of eggs needed to give potential success will be higher and the overall chance of future success lower.

How long before having children should I consider freezing my eggs?

Once the eggs are stored, the success rate is “locked-in” at the age they were frozen. The duration they spend cryopreserved has no bearing on the future outcome of treatment.

So, you could freeze them 2 or 10 years before you want to have children with similar outcomes. They key, as we have discussed above, is deciding at what age to freeze them.

Does undertaking egg freezing treatment increase the difficulty of conceiving naturally later on in life?

No, but this is a common misconception. In any given cycle, a number of follicles with eggs in them will be recruited from your stores ready to respond to your hormones and grow. In a natural cycle, in response to your natural “follicle stimulating hormone” (FSH) they will all begin to grow, before one becomes the dominant follicle that continues to grow from which you ovulate and release the egg within. The rest will in essence wither and die away before a new batch comes through ready for next month if not pregnant.

When we stimulate your ovaries with FSH injections for IVF or egg freezing all we are doing is making this more process more efficient by stimulating more of those that have already been recruited. As more follicles grow, this allows us to collect as many eggs as possible. We do not recruit any more than are already there so should have no long-term effect on your fertility or bring menopause on earlier.

Nevertheless, one of the non intended social consequences is the false sense of security that may lead to a further detrimental delay in trying naturally for a baby. Should the frozen eggs prove unsuccessful, they may subsequently be faced with the prospect of trying for a baby with fresh eggs at an older age.

Once frozen, how long can eggs be kept for?

The law permits you to store your eggs for any period up to 10 years, so routinely you will get an annual letter confirming that you want to continue to keep them stored.

In cases where you or your partner are prematurely infertile or likely to become prematurely infertile, you may store for longer up to 55 years if a medical practitioner certifies this to be true.

How does the egg freezing process work:

The initial steps (1-4) are similar to that in an IVF cycle


Ovulation Induction

FSH injections to stimulate the ovaries to produce multiple follicles (each follicle potentially containing an egg), over a period of approximately 2 weeks.


Monitoring response

3-4 scans (with blood tests) over this period to monitor the number and size of the follicles to help us correctly time when we should collect them.


Preparing for collection

Trigger injection when the leading follicle reaches 17-22mm to mature the eggs in preparation for collection.


Egg collection

The eggs are collected using a minor vaginal procedure performed under anaesthetic and under ultrasound guidance.


Egg freezing

Following collection the cells around the eggs are stripped away to identify which eggs are mature. These mature eggs are then cryopreserved using the vitrifcation process.


Future use

When needed these eggs can be thawed and fertilised using micromanipulation techniques (ICSI) that are required as the freeze / thaw process leaves the outer layer of the egg (zona pellucida) hardened.


Free Egg Freezing Virtual Open Evenings

While we continue to comply with Government recommendation regarding social distancing, all scheduled Open Evenings will be held as Online Virtual Open Evenings via Webinar. These will remain an opportunity to meet us online and have your questions about fertility treatment answered.

One of our fertility specialists will present information on the egg freezing options available at The Lister Fertility Clinic and an overview of the IVF process itself. Attendees will also have the ability to submit questions live and have them answered by our specialists.

These events are intended for individuals or couples who are contemplating fertility treatment and can help you to decide where to have your treatment.

For more information click here.

If you have any enquiries please call 02037334134

Book to see an egg freezing Consultant