When and why should I freeze my eggs?

Natalia Szlarb, MD, PhD
Gynaecologist & Fertility Specialist, UR Vistahermosa

Egg Freezing

From this video you will find out:

Freezing eggs - fertility preservation - why, how and when?

Fertility is not eternal, but there is a way we can extend the biological clock and gain some control over our reproductive future. In this webinar with Dr Natalia Szlarb, viewers learn what social freezing is; who it is for and why it may save you some crucial fertility struggles in a few years’ time.

Egg freezing

Egg freezing is a method of storing a woman’s unfertilised eggs so she can try to have children at a later date. Dr Natalia Szlarb starts by telling us that for many years, egg freezing (or ovarian freezing if it took place before puberty) was reserved for medical purposes only, e.g., for patients undergoing chemotherapy at a young age. The situation changed in 2012 when the American Society for Reproductive Medicine (ASRM) declared that non-medical social egg freezing was acceptable and no longer experimental. The procedure gives women the possibility to reach their educational, professional and financial goals before deciding on having a baby. It also allows them to find a suitable partner and create a mature relationship that would be the best environment for a child to grow.

Social egg freezing

Dr Szlarb says that social egg freezing has become a common and well-known procedure. Even big companies such as Google, Apple, or Facebook offer free egg freezing to their employees in order for them to form a family according to their chosen timeline. Dr Szlarb admits that there is no recommendation on what is the best age to freeze your own eggs in case of non-medical indications. However, age is one of the factors that oocyte survival and live birth rates depend on.

Dr Szlarb reminds us of an undeniable truth – women are designed by nature to have children when they are young. According to scientific literature, when a woman is 20 years old, 80% of her eggs are good. At the age of 35, 50% of blastocysts generated by her are healthy. This number changes as a woman grows older and when she is 40 years old, only 20-30% of her generated blastocysts are genetically normal. The best results through social freezing are therefore achieved when the procedure takes place before the age of 35. It is important to remember that live birth rates decline with increasing women’s age at freezing – regardless of the technique used.

Another significant factor the results of social freezing depend on is the number of retrieved and frozen mature oocytes. According to some American scientific papers, there are 8 eggs needed in order to achieve 60-80% probability of a child delivery (assuming egg freezing takes place before a woman is 35 years old). Dr Szlarb says that the goal is to have about 16-20 eggs frozen from each patient. The eggs are frozen with the use of the technique of vitrification that significantly minimises the cellular damage.

According to Dr Szlarb, there are a lot of challenges that the egg freezing process involves and they include: the size of eggs, high water content, unique chromosomal arrangement and meiotic spindle. However, with the invention of the vitrification technique, those risks are not decisive anymore. Vitrification is the key when it comes to the successful outcome of the whole egg freezing process. The available scientific literature from the years 2010 – 2015 shows a survival rate of 92% when eggs are vitrified in liquid nitrogen at minus 100 degrees.

Patients often ask about the differences in the success rates of IVF cycles with fresh and frozen oocytes. Dr Szlarb recalls one of the most important studies on donor eggs from 2010 (by Cabo A. et al.) showing that the fertilisation rate is 73-74% no matter if we use fresh or frozen eggs. Similarly, the differences in clinical pregnancy rates and ongoing pregnancy rates are almost non-existing (they oscillate around 1% in each of the cases). Later on, these results were also confirmed by studies relating to non-donor eggs that proved no statistical differences in fertilisation rates between vitrified and fresh oocytes.

Frozen oocytes storage

When it comes to the storage of frozen oocytes, the average time is between 6 months and 5 years before patients use them successfully. For now, the longest period of storage resulting in a live birth was 14 years.

At the end of her presentation, Dr Natalia Szlarb talks a little about ethical considerations. She highly values the Spanish law that does not discriminate against anybody in their quest to become parents and treats egg freezing as a women’s right.  Dr Szlarb understands well that women want to be independent and have control of their reproductive health. The doctor’s obligation is to raise their awareness of the important issue of egg freezing and help them to make the most of it. We have to remember that egg freezing does not guarantee IVF success – but it does increase the possibility of having a biological child in the future.

You may be interested in reading more about:

- Questions and Answers

I wanted to ask dr. Nathalia’s opinion on the recent research suggesting that a frozen embryo transfer could increase a cancer risk in children born subsequently?

I don’t know which papers you were reading but the literature that I have used to prepare this presentation is showing that there is no difference in the number of abnormalities in children born from frozen or fresh eggs. There is no strong data available that would prove there is a higher risk of cancer.

I am 41 years old with low AMH (about 0.8). In previous egg retrieval sessions I was getting about 10 eggs but not all got fertilised. What is success percentage in my case? And how many eggs should I freeze to give me a decent chance later? I heard that the chance of success for frozen embryos is much better than for frozen eggs.

The numbers that you’re showing (AMH = 0.8 and 10 frozen eggs) are amazing. I only wish you to repeat this kind of cycle. When you are over 40 years old, the problem we are facing is the poor quality of eggs and low fertilisation rate. If you have a partner that you believe you’re going to stay with for a couple of years and raise your child with, then I’d recommend you to fertilise the eggs and do the trophectoderm biopsy to see which of these fertilised eggs and embryos would develop to day 5 and which of them are healthy and genetically normal. If you have one genetically normal day 5 embryo of AB or BB quality, the chance that you would get pregnant is 70%. Nobody provides the statistics showing the number of eggs that you should freeze. You should definitely go for embryo banking with PGT-A to make sure that you generate genetically normal embryos. If you see that unfortunately all your eggs are genetically abnormal, then the highest step of the reproductive medicine that we can offer you is egg donation.

Can you please explain one more time IVF with frozen eggs? You mentioned that the fertilisation rate is similar between fresh and frozen eggs. How about single success rate per a transferred embryo?

It is a very good question. The fertilisation rates are similar but if your eggs are frozen before you are 35 years old, the majority of them are genetically normal. You generate good embryos and your success rate is between 60 and 80% per transfer. If you freeze your eggs when you are older than 35 years old, a lot of eggs that you generate will be genetically abnormal. That’s why your success rate then is only 20-30%. So how can we optimise the pregnancy rate from frozen eggs after 35 years old? We can develop embryos to day 5, we can do PGT-A and test them genetically and then we know which of them are healthy. Then, the success rates with genetically normal embryos after PGT-A (for women over 35 years old) are higher – 70% per transfer. And according to literature, an average pregnancy rate for frozen eggs over 35 years old is only 30% – without PGT-A.

Do stims make you produce more follicles or just mature whatever follicles you produce yourself? I had low AFC (4) and low AMH (0.6) when we had our consultation.

The stimulation makes you grow more follicles and usually makes you produce more eggs. AMH is very important. When your AMH is more than 2 ng/ml (which is about 14 in the UK), then I expect 20 eggs. When your AMH is between 1 and 2 ng/ml (between 7 and 14 in the UK), then you will generate 10 eggs. When your AMH is under 1, we expect less than 10 eggs. So let’s see how the cycle goes and if with 4 follicles and AMH = 0.6, I’ll have 4-5 eggs – I will be over the moon. Then I will be convincing you to do the so-called ‘egg banking’. After 2-3 months, I will recommend you repeat the cycle and freeze more eggs. So at the end of the ‘egg banking’ process, you will have 16-20 eggs frozen.

Can you also explain the stimulation process? I cannot stay for 21 days away from work… Do I really need to make scans every few days? Do you cooperate with some particular clinics in Ireland?

Try to imagine 21 days away from home and the summer holidays in Spain – lovely, isn’t it? ? . But this is not how we work. We want you to be here just from Monday to Saturday – basically for one week. How do we schedule this? We put patients on birth control pills. We use them to synchronise the follicles. When you do the ultrasound of your ovaries, you see that your follicles naturally have different sizes. And then through birth controlling pills, we are synchronising them. You stop taking birth control pills when it is convenient for both of us – when, e.g., I have an available spot for you in the lab and in the operating theatre and I can adjust it to your work, birthday or whatever you want. And then the first 7 days of injections are in your home country. Yes, we do work with clinics in Ireland – we work with GCRM-Belfast and dr. Kent Ayers in Dublin. We have doctors there who support us. They will basically need to do two ultrasounds and two bloodworks from you – and we’re going to write down when exactly. Usually, the first ultrasound is done on Friday when you stop with birth control pills on Tuesday. Then when everything is ok, you start putting injections on Sunday. The second ultrasound is on the following Thursday. This is how you run the first part of the cycle, doing two ultrasounds and putting injections every day. For the second half of the cycle, you have to be in Spain from Monday till Saturday. We’re going to see you every two days. When we plan egg retrievals, we usually do them between Wednesday and Saturday. And then we have to see you every two days. So basically you can calculate it – when you’re arriving on Monday and then I plan the egg retrieval on Wednesday, I see you twice in our clinic. You need to do two ultrasounds in your country and two ultrasounds in your clinic. Of course, I also know the cycles where patients are coming to us every other day for 14 days. I remember that once in Detroit area in the US, the sonographer and the nurse, who were responsible for the IVF unit, were coming to work around 5 a.m. and till 8 a.m. they were doing the scans and all the bloodwork. So when we were coming to work at 9 a.m., we had all the results. You can imagine that in Spain it is not doable ? . Generally, we know that in the first half of the cycle nothing is really happening. The patients are putting injections and the follicles are not growing quickly enough for you to ovulate on day 3 or 4 of the cycle. So we’re planning the first ultrasound in your home country on day 5. After day 5, we are putting injections. And then in the second half of the cycle we cannot miss two moments. The first one is when the follicles are 16 mm – I’ve got to administer the antagonist so that you are not going to ovulate. The second moment is when the follicles are 18-20 mm and this is the moment when we have to think about triggering the ovulation. This is when we have to plan the egg retrieval. So then I have to see you every other day – and basically it is just twice. Sounds like a plan? ?

Is there an age limit for freezing your eggs – is it still possible and worth it to freeze eggs when you are over 40?

The question is: how much over 40 are you? I had a colleague, a dentist, she was French. She lived in Dubai. She was flying to us at the age of 42 and freezing her eggs. I have 20-25 of her eggs frozen – but I don’t know how many of them are genetically normal. If you are 40-42, it’s worth it. At the age of 43, it is going to be very difficult.

If you only have 3 eggs, is it worth freezing them at age 48?

I have to be honest with you. We all feel young and look amazing, but after 43 years old, it’s almost impossible to find genetically normal embryos. One of the oldest patients that I have seen in my life, who generated a genetically normal embryo, was 45. Afterwards, she put that embryo back in herself, we had 6 weeks of pregnancy and then she had a miscarriage at week 6. So the answer to your question is: there is no point in freezing your eggs when you are 48 years old because the majority of them are genetically abnormal. Basically, when we talk about serious reproductive medicine and pregnancy rates, we have the best results when we generate eggs and embryos before 42 years old. The majority of our patients at the age of 43 are undergoing egg donation.

I have read that the survival rate of frozen embryos is higher than frozen eggs. I am single now and wonder if I should fertilise some of my eggs with donor’s sperm and freeze the rest in case I have a partner in a couple of years. Do you think I should give birth before I reach 40?

I raised a beautiful daughter myself. It’s an amazing experience. The first 2-3 years are tough but when kids get older, we’re best friends. So if you can allow yourself professionally and economically to raise a child, then go for it with donor’s sperm. Sometimes I have cycles with young women who can generate even 40 eggs. And you do not want to over-generate the number of embryos. So we do the following: we fertilise 20 and we freeze 20. And when you are 35 years old, out of 20 eggs I expect 10 blastocysts – and 5 of them are genetically normal. So basically, in one cycle we can have entire family planning. In Spanish legislation, I can treat you until you are 50 years old and 11 months. So there are some girls who are delivering children from our treatment when they are 52 or 53. And they’re fine. But the younger you are, the better it is. The more strength you have. So I definitely recommend you to fertilise some of the eggs with donor’s sperm and to raise your own best friend in life. And then, when a proper partner is going to come one day, it’s like your personal investment. It takes time to find somebody and to decide to have a child with him. So leave a couple of your eggs frozen, but first make sure you have a child out of IVF treatment. When you are 40, we definitely recommend PGT-A – it means preimplantation genetic testing of your embryos for aneuploidies. We have to be aware that when we are older than 35 years old, the majority of embryos which we generate are unhealthy. So when it comes to being a single mum, I can only wish you to make it happen as soon as possible. And definitely test your embryo genetically to make sure it’s healthy.

Is there any point going though an IVF cycle myself if my AMH is zero and no periods?

With AMH which is zero and no periods, you have all the signs of being menopausal. So an IVF cycle does not make sense at all. It is always wise to confirm that your AMH is really zero. Do the transvaginal scan to see if there are no antral follicles. There are different reasons why girls do not have periods. But when your AMH is zero, you have no periods because probably you are menopausal. And then the best thing that you can do for yourself is egg donation. And we can treat you until you are 50 years old and 11 months.
Fertility coaching: what is it, and why might I need it?
Transparent egg donation: the new quest
What is the role of the endometrium in Repeated Implantation Failure (RIF)?
Fertility Secrets Unlocked: The top 3 things that are affecting your fertility and how to fix them
Which supplements should I consider before, during, and after IVF?
What is niPGT-A (Non-invasive PGT-A Preimplantation Genetic Diagnosis without biopsy) and what it consists of?
Natalia Szlarb, MD, PhD

Natalia Szlarb, MD, PhD

Dr Natalia Szlarb a Gynaecologist & Fertility Specialist at UR Vistahermosa, Alicante. She graduated from a medical university in Poland in 2002 and then worked in gynaecology and obstetrics wards at several German hospitals. She also participated in international internships in Egypt, Brazil and Poland during her medical studies. In 2011 Dr Szlarb obtained her PhD in Immunology in the United States of America. She has extensive experience in IVF with donor eggs and is known by patients as a friendly and warm doctor. Dr Szlarb speaks fluent English, Polish, German and Russian.
Event Moderator
Sophie Mazurek

Sophie Mazurek

Sophie is a branding and Internet marketing specialist with 10+ experience. A designer of communication throughout all channels. Content strategy maker and video storyteller.  She speaks with images and paints using words. Working from a sparkle of an idea to develop it step by step to the final concept. 
Have Questions about PGT-A and IVF?
Join our live event to directly ask your questions to three IVF experts.