Egg Freezing – The Basics

A new patient consultation for egg freezing is rapidly becoming one of my favorite patient visits. These young women set up an appointment to discuss their future fertility and I am all about it! They come in at different stages in their lives- some are single, some are in a new relationship and they don’t want the pressure of “the clock”, some are even married. The one thing they all think – is that they may want children in the future; the one think that all know – is that they are not ready for children right now.

Just so you know, oocyte cryopreservation (egg freezing) has been around for awhile (almost as long as traditional in vitro fertilization or IVF). That being said, it was not until 2012 when it lost its “experimental” label and it is now offered as a standard practice. Why did it take so long for egg freezing to be considered standard of care? There are multiple reasons; most importantly – older freezing techniques (ie. slow freeze) was traumatic to the eggs and caused significant damage at thaw and fertilization. That lead to less than ideal success rates and if you cannot use the eggs later on down the road, what is the point in going through the whole process to being with?

Now that egg freezing is no longer experimental, it is being offered by many fertility practices (as well as some specific egg freezing centers). This has its positives, but it also has some negatives. Just like IVF, not all centers have the same success rates. I mention this because I think it is important for women who are considering egg freezing to ask questions of their doctor and the IVF laboratory before they get started. How long have they been freezing eggs? Do they have any thaw data? Do they have pregnancy data?

My opinion? You definitely have the right to know the answers to these questions.

In this post, I want to address some of the questions I get most frequently at an egg freezing consultation:

1. How long do the eggs last for?

It is safe to say the frozen eggs can remain frozen for longer than you could need them. The main concern about egg freezing has always been how well they freeze and then thaw. With the current freezing techniques (vitrification), we see very high thaw rates (>90%) and that does seem to change with the length of time frozen.

2. How many eggs should you freeze?

This answer to this question is not one size fits all. There are many factors involved in deciding how many eggs a woman should freeze. The biggest factors:

a) Patient Age- As a woman ages, her eggs have a lower chance of developing into a baby. Most recent data and some very helpful predictor calculators, show that each unfertilized egg has about a 4-10% chance of becoming a baby in the future. The younger the woman, the higher the chance of success.

In women <35yo, there is about an 8-10% chance of live birth per egg. Stating it another way, Doyle, et al. reported that in those women <38yo who retrieved 15-20 eggs, they had a 60-80% chance of one live birth.  In older women, they required higher numbers of frozen eggs to achieve a live birth.

b) Family planning goals- It sounds obvious, but many do not always think about their long term family planning goals. The more children you desire, the higher the number of eggs you should freeze.

Most importantly, Iadvise women that this is all just predictions. We are hopeful that they will be the “norm,” but egg freezing is not a guarantee of a baby.

3. When should I do it?

In my opinion, the ideal age to freeze eggs around 32-35 years old. Of course there are always exceptions. You may need to freeze them earlier if you have a low ovarian reserve, a family history of early menopause or if you will be undergoing treatment for cancer. If you freeze at younger than 32 years old, you are less likely to use them (ie. you might get married and conceive well before you would ever need them). If you freeze them at an older age, you will have a lower chance of success, but that is still better than not trying at all.

4. What if I find a partner, should I use the eggs or just try to conceive?

I typically recommend you try to conceive first (if you are still in the age range for spontaneous pregnancy). Like any couple who are trying to conceive, if you are >35 years old and not pregnant in 6 months then you should come back to discuss your next steps.

5. How do we get the eggs out?

This process is very similar to an in vitro fertilization cycle. You take similar medications and undergo the retrieval to remove the eggs from the ovary. Where it differs is that instead of fertilizing the eggs, the embryologist freezes the mature eggs immediately. I will actually elaborate more on this process in my next post.

If you cannot tell, I am a huge proponent of egg freezing. I think the advancement in technique and the marked improvement in success rates certainly validate its use.

In my next blog post, I am going to discuss the steps of egg freezing. Keep you eyes open for it!

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