Dr César Díaz García, Medical Director at IVI Clinic London is talking about fertility preservation and egg freezing – indications and outcomes.
This is a kind of question that I cannot answer. The best time is not based on a medical aspect, from a medical point of view, the younger you are, the best. From a practical point of view, patients will freeze their eggs whenever they think that they need it. If you are f. e. are in a stable relationship and you are very young, and you are thinking about having kids tomorrow so to speak, probably you don’t need to freeze your eggs, especially if you only want to have one child.
On the other hand, maybe you don’t know when you’re going to be a mom, and you don’t want to be in a rush, anytime is a good moment to freeze your eggs. It really depends on the characteristics of the patients and also on personal preferences, so in order to answer this question, I think we need to know more about the personal circumstances of the patients.
In fact, we have two questions here. The first one: what is the right amount of eggs depends on your ovarian reserve, and it also depends on how many children do you want to have. If you are thinking only about having one, you don’t need to freeze as many eggs as if you want to have more than one. Having said that if you have a good ovarian reserve which is the case in a patient at the age of 30, most of the time one cycle of ovarian stimulation will be enough to have a very good chance of having at least one live birth. If you are thinking about having more than one more child, maybe you will need to do more than one round, and this is what you can see on one of the graphics that I showed you before. Let’s say for one child, at the age of 30 usually one round of IVF is needed.
The process is very simple, especially from a medical point of view. When someone wants to use the frozen eggs, we need to fertilize them with the sperm of the partner or with the sperm of a donor, and we do that by doing ICSI, which means Intracytoplasmic Sperm Injection, so we take the egg, and we inject directly one spermatozoid inside, we do not do a classic IVF, we do not let them mix naturally, because after the freezing process the external shield of the egg what we call the zona pellucida becomes so hard that the eggs spermatozoids cannot penetrate it, so we need to inject the egg inside, and we do that in the lab. Then we let the embryos grow, and after five days of growth when the embryo reaches what we call the blastocyst stage, we put it back into the womb.
To put it back into the womb, we previously prepare the uterus to be receptive, to do that we just basically give pills, mimicking the natural cycle, so basically natural estradiol and natural progesterone. There is no need for injections at that point. It’s very friendly, it usually takes about 15 days, then we put the embryo back, to put the embryo back there’s no need of sedation, we can even do it in a consultation, we usually do it in the operating theatre, just beside the embryology lab because we don’t want to move the embryo and 11 days later you will do a pregnancy test.
We usually tend to present data in a categorized way, so we tend to do groups, but age is what we call a continuous variable. It does not mean that for example after 35 everything is going to be dramatically different, so everything drops slightly step-by-step, so obviously the younger you are, and you do it, the better results you’ll get. A two-year delay, when you are 34 as compared to 36, it will have an impact, I cannot say the opposite, but the impact is not going to be as high as for example if you compare 38 versus 40. Then the gap even it is the same time interval, the gap is huge. In terms of results, I will say that at that specific point around 35 it is when things they really get to drop a little bit quicker, so if you are already thinking about it and you are 34, my advice would be to do it now.
Obviously, we really respect the right of the patient to decide it, as far as the patient has the information to make a decision and if the patient is aware of the chances at such age and if you want to do egg freezing, it is a very valid treatment. It happens quite a lot that the patients cannot become a mom, or they don’t want to become a mom at the age of 40 for many different reasons, and maybe they are considering doing it 1 or 3 years later. What I can tell you for sure, is that whenever you try one or two years later is going to work much much worse, so if you already know that you are going to postpone your maternity, it is better to freeze eggs at the age of 40 than trying to do a fresh IVF at the age of 42, that’s for sure. Then the results that you can expect are not going to be those of a woman at the age of 35. The pregnancy rates are going to be lower but still, we can achieve very good pregnancy rates. So at those ages, we usually have a very deep discussion with the patient to give very realistic information about what they can expect, we give figures based not only on their age but also on their ovarian reserve. It’s not the same being 40 years old and has 20 eggs in one cycle, then being 40 years old and getting only one egg, that can also happen. The scenarios can be very different in the same age group.
Yes, it is true. It’s not so different f. e. the embryo survival rate in patients who have euploid blastocyst in our clinic is 98%, and the survival rate of vitrified eggs below the age of 35 is between 90- 96%.
Having said that the survival rate of vitrified eggs after the age of 38 f. e. is lower than that, it is around 80-85%. Then also you have to be very conscious because people think that it is better to generate embryos, so my chances of having my fertility preserved is going to be higher, that is not true. If you confirm everything at the beginning of the process, let’s say today before you have started the process, what is going to happen is that when we do the ovarian stimulation, we are going to have much more eggs than embryos. Then when we retrieve the eggs maybe not a 100% of them are going to be mature, but even those that are mature, not 100% of them will fertilize and not all the embryos that are fertilized the first day will reach the blastocyst stage. We only freeze the embryos at the very end of the process which means that f. e. in a patient at the age 40 years old on average we usually vitrify 2 to 3 blastocyst, so yes those blastocysts will survive better than the eggs, but you should compare the chances of having a baby with 10 vitrified eggs as to those having a baby with having 2 or 3 blastocysts because that’s what we usually get. The thing with vitrified embryos is that you will be 3 or 4 steps ahead in the process.
You will probably know how good are your eggs because it can also happen that you vitrify your eggs, they look beautiful, but you have to be aware that 15% of the population have fertility problems. What if you are within these 15%, very likely you will find out about it until the moment comes to using the eggs. This is why when I talk to my patients, I always say, please keep in mind that even if you have a lot of eggs, we cannot guarantee a 100% success rates because that’s almost impossible in biological science.
The problems can happen in between, and obviously, the more you are advanced in your fertility journey, the more information you will have. So vitrifying embryos is more reassuring in a way that you will have more information, but from a practical point of view at the end of the process you will get to the same point, but you will know it before.
There’s also another implication especially if the patient is in a relationship, they usually tend to vitrify the embryos using the sperm of the partner and then there is also very important implication because while the eggs strictly belong to the patient, the embryos belong to the couple so both partners, so for whatever reason the patient’s they Split, it can happen that even though they have embryos, they cannot use them in the future because they need the permission of the partner to do so. Unfortunately, in my experience when couples want to get permission to get the embryo back is quite difficult.
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