In 2024, I went through a cycle of egg freezing. I hope this blogpost will be a helpful resource for people who are also considering egg freezing. I’m based in the UK so part of this information will only be relevant to UK patients but most of it should be applicable to everyone.

I will share my own experience but also draw on a large dataset of IVF treatments in the UK to give some evidence on IVF success rates and egg freezing. The data comes from the Human Fertilisation and Embryology Authority (HFEA), a government authority that regulates fertility treatment in the UK. All fertility clinics (public and private) have to report all of their treatments to the HFEA which means that the data captures close to 100% of all IVF and egg freezing cycles in the UK. It’s the longest running database of its kind, going back to 1991! The data can be accessed here and is currently available up to 2018.

The way the data is organised means that there is one entry for each treatment cycle but multiple treatments can’t be linked to individual patients. However, I can filter for patients who have never had any treatment before. I look only at the first treatment in order to avoid selection effects where patients with a bad outcome are more likely to go for further treatment. The data has coarse age groups to protect anonymity so I am restricted to using those for my analysis.

Why freeze your eggs?

The main reason to freeze your eggs is that fertility declines strongly with age, but this decline is basically entirely due to the quantity and quality of your eggs declining, and not due to a decline in the ability to carry a pregnancy to term. This means that if you freeze your eggs and use them later in life, your chances of getting pregnant and having a baby are mostly determined by the age at which you froze your eggs, as opposed to the age at which you use them.

We don’t have very reliable data on this yet, since egg freezing has only recently become more common. Ruxandra Teslo has a great summary of Cascante et al. (2022), one of the best studies on the efficiency of egg freezing. The data that we have so far seems to support the hypothesis that freezing your eggs gives you success rates that are similar to doing IVF at a younger age. The main caveat here is that the median age at freezing in the Cascante et al. study is 38.3 years and the median storage time is 4.2 years. That means that we don’t have much data yet on what happens when you freeze eggs in your twenties and use them much later. 

I stumbled upon the fact that the age of the eggs is so decisive when working with the HFEA data for my research. We can see this when looking at how strongly success rates for IVF differ by whether patients are using their own eggs or donor eggs. (Keep in mind that I’m only showing the success rates for the first treatment here; cumulative live birth rates, i.e. the chance of a live birth after several cycles, are higher than this.)

Source: Public HFEA data 1991-2018, own calculations

On the left, we can see the strong decline in success rates with age when patients use their own eggs. On the right, it’s clear how stable success rates are when using donor eggs (which usually come from younger donors). Even the oldest patients can achieve success rates similar to the youngest ones when they use donor eggs!

The above graph summarised all cycles over the whole time period of the dataset. Unfortunately, it also doesn’t look like the overall improvements in the technology over time are benefitting older patients. Zooming in on the two oldest age groups who are 43 and older, we can see that success rates with patients’ own eggs have barely improved at all and are under 5% for the first treatment. The data using donor eggs is noisier since there are fewer treatments overall but we can see a clear upward trend in success rates, making the gap between the two options even bigger.

Source: Public HFEA data 1991-2018, own calculations

A lot of people think that IVF is a very reliable option if they end up wanting kids later in life and don’t realise that this is not quite true: IVF is actually quite unlikely to work at an advanced age if you want to use your own eggs. In the whole dataset, there are 14,603 patients aged 43+ who tried IVF using their own eggs and only 2,076 cycles where at least one live birth occurred. That’s roughly 14% of patients who manage to have a baby at that age with their own eggs. Due to the limitations in the data, this is of course not a perfect measure of the total live birth rate you can expect, but it’s probably a good approximation.

Seeing all these numbers made me decide to freeze my eggs. Since I was sure that I wanted kids at some point in my life and it was unclear when my partner and I would be ready to start trying, it seemed like a sensible investment to go through the egg freezing process. Of course, this is a personal choice and there are important downsides: It is quite expensive, comes with the risk of potentially serious side effects, and it is unclear whether you will ultimately actually need to use the eggs.

Egg vs. embryo freezing

If you have a partner, you might want to consider whether to freeze eggs or embryos. There are two main advantages of freezing embryos instead of eggs. The first one is that survival rates after thawing are slightly higher for embryos compared to eggs. The second one is that you have less uncertainty. Ultimately it is the number of embryos that matters for how many chances at a live birth you get, so if you freeze eggs, you’re still one step away from knowing the number (and quality) of embryos. This can make it harder to know how many eggs you should be aiming to freeze and potentially give you less peace of mind. The main advantage of freezing eggs is of course that you can still use the eggs if you break up with your current partner.

For frozen embryos, we see very high survival rates. For example, Brolinson et al. (2023) find a thaw survival rate of 99% based on almost 7,900 embryos thawed for transfer and embryo survival rates are generally thought to be over 95%. The numbers that I can find for the survival rates of eggs after thawing are a bit more mixed. This is partly because egg freezing has improved in recent years with a transition from slow freezing to vitrification. Cascante et al. (2022) report a survival rate of 79%. Cura Ruiz et al. (2024) find that 85% of thawed eggs survive. The London Egg Bank claims to have a survival rate of 93% and my clinic also told me that these days they expect more than 90% of the eggs to survive. My best guess from the information I’ve seen is that with modern vitrification methods, a survival rate of 90% is realistic.

That being said, the differences in survival rates are small enough that the expected number of embryos that you end up with, is not that different. Let’s assume a conservative 80% survival rate for eggs and 99% for embryos, a fertilisation rate of 60% and that you start with 20 eggs collected. Then you would expect to have 9.6 embryos after egg freezing, thawing and fertilisation, and 11.9 embryos after fertilisation, embryo freezing, and thawing. If we assume the most optimistic egg survival rate of 93%, freezing 20 eggs would leave you with 11.2 embryos in expectation.

The process

The egg freezing process usually starts with a fertility assessment. For me, the assessment was measuring my anti-Mullerian hormone (AMH) and doing a vaginal ultrasound where the follicles in my ovaries were counted (this is the antral follicle count, AFC). The AMH is an indicator of your ovarian reserve, i.e. the quantity and quality of your remaining eggs.

My AMH was pretty low for my age (11.1 pmol/L, which is below the 10th percentile in the 20-29 age group) but my antral follicle count was 20 which is a good value. We discussed a bit whether my low AMH might be due to the fact that I had been on the progestogen-only pill for quite a long time at this point. There is some evidence that hormonal contraception can lower your AMH. Unfortunately, the specialist at the clinic couldn’t give me clear advice on whether it would make sense to come off the pill for a few months before doing the treatment in order to give my AMH time to recover. I ended up coming off the pill for one menstrual cycle before starting the egg freezing with the next cycle. I am now waiting a few additional months to see whether my AMH goes up and will do another cycle after roughly half a year off the pill.

After deciding to go forward with the egg freezing process, there are some formalities that you have to go through. In the UK, this is all regulated by the HFEA and there are a bunch of forms to fill out, for example to specify how long you consent to your eggs being stored. You also have to get a Hepatitis B and C, HIV, and Chlamydia test. This can either be done at the IVF clinic or you can try and get these through your GP or a sexual health clinic which might be cheaper. It’s good to be aware of this and plan this early because it can potentially delay the start of the cycle. My clinic didn’t tell me until quite late and then it was a bit of a struggle to get everything done so that I could start with my next period.

Once all this is done, you’re ready to get the medication and start the injections. There are different cycle protocols but the most common one is the “short protocol” which I was on as well. This means that the whole process is roughly two weeks and you do two different types of injections (+ the final trigger injection). I started on the second day of my period. For the first five days of the treatment, I did injections of Meriofert (this has follicle-stimulating hormone and luteinising hormone) in the evening. On the sixth day, I started adding morning injections of Ovamex (this is a gonadotropin-releasing hormone antagonist).

The Meriofert injections stimulate your ovaries to produce multiple mature eggs. Basically, in each menstrual cycle you usually have several follicles in your ovaries that each have the potential to ripen to a mature egg. However, in a typical cycle only one of these follicles transforms into an egg. The extra hormones are supposed to make all of the follicles grow. The Ovamex helps to control this process and to prevent premature ovulation.

I had a Zoom appointment with one of the nurses who showed me how to do the injections. Potentially, it would have been better to do this in person because I did end up feeling quite intimidated with my first injection. I would definitely recommend having at least one other person there who can look at the instructions with you. The injections are subcutaneous which means you usually do them either by pinching your belly or your thigh.

The injections were overall pretty okay and after the first one, it started feeling relatively easy. The needles  are very small so it’s not really painful (probably comparable to or less so than having a blood test). I did find the Ovamex injections a bit less pleasant and they usually left my skin itchy and red for 30 minutes or so.

After doing the injections for roughly a week, I went to get an ultrasound at the fertility clinic. The purpose of this is to both monitor for side effects and to see how far along the follicles are. They count all the follicles on each ovary and measure them. This is repeated every other day until enough follicles reach a certain size (this is usually between 12 and 19mm).

If the size threshold is reached, the last step is to do the trigger injection and egg collection. The trigger injection has to be done at a very precise time because the egg collection is supposed to be exactly 36 hours after the injection. My trigger was Ovitrelle (which is hCG, aka the pregnancy hormone) and I did it on the evening of day 10 which meant my egg collection was on the morning of day 12.

To collect the eggs, an ultrasound probe is inserted into the vagina to help guide the procedure. A thin needle is inserted as well and goes through the vagina to reach the ovaries so that the follicles can be aspirated.

You will usually be sedated for the egg collection so you will have to have someone to pick you up, get you home, and stay with you for the rest of the day. I took paracetamol one hour before the egg collection, which is what the clinic told me to do. They gave me what they called a “semi-conscious” sedation (so it’s not like general anaesthesia) but it did completely knock me out and I don’t remember any of the procedure. I had a bit of bleeding and slight pain afterwards but it was really mild and I didn’t end up taking any more painkillers.

They told me they collected 14 eggs immediately after the procedure. However, this is usually higher than the number of eggs that actually ends up being frozen. They basically try and get all the follicles that they can see but some of them won’t contain an egg at the right stage of maturity. I got a call from the embryologist later that afternoon and they updated me that they were able to freeze 8 eggs. This is relatively low for my age and you would usually expect around 12-15 eggs. I’ll talk about numbers in more detail below!

Potential side effects

There are various side effects that you can get from the hormonal injections. The main one I was warned about was that your ovaries can get twisted because they’re so enlarged. If this happens, you need to have a small surgical procedure. To prevent this, you’re not supposed to do vigorous exercise while going through your egg freezing cycle.

The main serious side effect that some people get is Ovarian Hyperstimulation Syndrome (OHSS). The symptoms of OHSS include abdominal pain, nausea, and vomiting and in more severe cases, shortness of breath and blood clots. There is also a small risk of a perforation of your bladder or bowels when the eggs are being collected.

I got lucky and had almost no side effects. The main thing that I found annoying was not being allowed to exercise for a while. During the last 2 or 3 days leading up to the egg collection, I started feeling my ovaries a bit more. This persisted a bit after the egg collection and fully went away with my next period. 

Except for the exercise, I was able to do everything I normally do and only ended up taking one day off work on the day of the egg collection. This can vary of course, so it’s best to plan the egg freezing process during a time when you don’t mind your schedule being disrupted a bit.

Numbers!

How many eggs can you expect at what age and how many do you need to have a good chance of a live birth? I decided to take a closer look at the UK data I’m working with to get a sense for what outcomes you can expect.

Every treatment in my dataset has a short description of the reason for treatment. That means I can filter all treatments that are done primarily to store eggs or embryos. As before, I focus my analysis on new patients undergoing their first treatment. Here is an overview of the number of new patients undergoing storage cycles in the UK.

Source: Public HFEA data 1991-2018, own calculations

Egg and embryo freezing has become a lot more popular in recent years! However, the overall sample sizes are still relatively small. Unfortunately, exact numbers of eggs and embryos are only reported up until 2016. I therefore look only at data from 2012 to 2016 in order to use the most recent data that I have exact numbers for.

Most people decide to freeze embryos for storage so there are fewer actual egg freezing cycles in the data. The graph that I’m showing below distinguishes between those cycles that are for storing eggs only, those that are for storing embryos only, and all cycles (which includes some cycles that are for storing both, embryos and eggs).

For the youngest two age groups, there is a bit of a difference in the average number of eggs between these different storage types. While egg collection cycles for patients aged 18-34 yielded an average of 11.7 eggs, for embryo storage cycles it was 14.9. In the 35-37 age group, the difference is smaller, with 10.6 eggs from egg storage cycles and 12.0 eggs from embryo storage cycles. I’m not sure why this is the case.

The number of eggs collected declines with age as expected. Looking at all storage cycles, the average number of eggs is 13.9 for the youngest age group and 3.6 for the oldest age group. It is important to keep in mind that the quality of eggs is also likely to be lower at older ages. That means you can expect to collect more eggs from an egg freezing cycle at a younger age and will also need fewer eggs for a good chance of a live birth.

Source: Public HFEA data 2012-2016, own calculations

I’m particularly interested in the youngest age group since the best time for freezing eggs is under 35. Let’s look at a histogram of the number of eggs collected to get a better sense of the variance in outcomes. I use all storage cycles for this. In the youngest age group, it is very unlikely to not collect any eggs at all. The 25th percentile is 8 eggs and the 75th percentile is 19 eggs.

Source: Public HFEA data 2012-2016, own calculations

These numbers give you sense for how many cycles you might need to freeze a certain target number of eggs. How many eggs should you freeze? This calculator is based on three different datasets and allows you to calculate the probability of at least one or two live births with a given number of frozen eggs at a certain age. I’m personally targeting 20 eggs, which for someone under 30 gives a probability of at least one live birth of 74-95% and a probability of two or more live births of 38-80%.

How many cycles to go for and how many eggs to target depends on several factors. One is of course how strongly you want to have children and how many children you’d ideally like to have. Then it depends on how physically taxing the process is for you since the side effects can differ a lot in how bad they are. There is the financial consideration as well, having to pay for each cycle separately.

One pretty unambiguous factor is that it’s best to do egg freezing as young as possible. The quality of your eggs declines over time which means that you need more eggs to have a good chance of a live birth. As we have seen above, the expected number of eggs per egg collection cycle declines with age as well so that you need more cycles to reach a certain number of eggs. Since the storage limit for the UK is now 55 years, there isn’t much pushing against doing it as early as possible, except that you have to pay for more years of storage (which is a lot cheaper than an additional cycle).

Costs

In total, I paid roughly £6,700 for the first cycle. This includes the fertility assessment with consultation, the actual egg freezing cycle with one year of storage, and the medication.

It’s really important to be quite careful when you try to figure out the cost of the treatment. Both of the clinics that I compared had a “cycle package” for egg freezing that had similar costs. However, the cheaper clinic had the medication and the blood tests included in that, while the more expensive one didn’t. When the medication costs are not included in the package, they can be variable: The dose of the medication is higher the lower your AMH is, which means you might have to pay more. It’s a good idea to check this all as carefully as possible and to get a cost plan in writing before you pay for your cycle.

My clinic had a very wide range for the medication costs (between £900 and £2,100). When I asked them to give me a more precise estimate, they told me it would be “around £1,500” but it ended up being £1,950. Since they only made my treatment plan and figured out how much medication I needed after I had paid for the cycle, I felt kind of tricked by the medication costs being so much higher than they initially said.

The second cycle will be a bit cheaper because the clinic offers a discount for the second cycle and I also have some medication left over from the first cycle that I won’t have to pay for. I expect that the total cost for two cycles will end up being roughly £10,000.

If you’re comfortable donating some of your eggs to someone else, one possibility to lower the cost is to take part in a “Freeze and share” scheme. This means that you can freeze your eggs for free but will have to donate half of the eggs collected. You have to be young enough for this to be an option and there are also strict screening criteria in terms of your own health and your medical family history.

Takeaways

• Egg freezing has been becoming more popular but it’s still rare for people to decide to freeze their eggs in their twenties when it has the most potential to help extend your reproductive window.
• The younger you are when you freeze your eggs, the higher the quality of your eggs, the fewer cycles are needed to reach a target number of eggs, and the better your chances at a child later.
• The data that we have so far is really promising about the outcomes we would expect for eggs frozen at a young age but the data is still sparse.
• The main downsides of egg freezing are that it’s an invasive procedure with potentially serious side effects, it is expensive, and there is uncertainty over whether you will actually need to use the eggs later.
• Getting just the initial fertility assessment (measuring antral follicle count and AMH levels) can be a good, easy, and relatively cheap way of getting a sense of whether you are at increased risk of age-related infertility and whether egg freezing would be especially beneficial for you.
• I personally had a good experience freezing my eggs and would recommend it to anyone who wants kids and doesn’t know their timelines yet.

Thanks to Ben Snodin, Denise Melchin, and Steve Newman for reading a draft of this post and helpful comments.