Clara Colomé, Medical Deputy Director at Eugin Clinic, is explaining social egg freezing and fertility preservation options for patients.
Several changes have occurred during the second half of the 20th century. At the beginning of the 21st century, first, women started working outside the home and many effective contraceptive methods appeared that allowed women to decide whether they wanted to become mothers or not. This is a very important social demographic change, but it confronts the fact that the best biological age to become a mother should be around 18 to 30 years old. However, during this period time is well women are developing their professional careers, they are finding their place in the world, and sometimes this leads to a conflict of interest between society and biology.
The graph shows that the mean age of first birth for women from the 1970s has been steadily increasing all over the world. In Spain, the mean age for the first child is almost 32 years old, but the mean age in the European countries is 28.7 years old. The problem is that women have an ovarian reserve, which is the number of eggs in their ovaries since birth, and they are used until they are finished. That means that with age, there is a decline in fertility chances, and over the age of 35, it declines faster, and after 40, it just goes down very fast. On the other hand, there is also a risk of miscarriage, which also increases with age. The eggs that remain in the ovaries might have some alterations because they’ve been there for 35-40 years. At 40 years old, the chances of having a miscarriage are higher than the chances of having a child if you get pregnant.
Therefore, more and more women decide to use social freezing and postpone motherhood. How does this work?
Every month there’s an egg that is selected from many of them in the ovaries, and it’s ovulated mid-cycle. The idea of fertility preservation would be to stimulate your ovaries with some medication to develop more follicles that would be lost otherwise. This medical treatment lasts for about 8-10 days, and there are 2-3 checkups during the procedure with an ultrasound or a blood test to make sure that your ovaries are responding correctly to the treatment. At a certain point, when a response is correct, the eggs are retrieved through the vagina with a very simple procedure.
Patients often ask about the number of eggs that are usually retrieved. There is a very interesting article published by Goldman in 2017, it shows the probability of having at least 1 live birth at home depending on the number of the mature good quality oocyte. In patients who are younger than 35 with 10 eggs, the chances of having a child at home afterwards are 80%, which is high. On the other hand, a patient who’s 44 years old to have a 50% chance of having a child needs to have over 80 vitrified oocytes, which is a lot. Therefore, the younger the woman who vitrifies her oocytes is, the fewer oocytes she needs to have at least 1 child. That’s one of the reasons why after 40 years old, this technique is not usually indicated.
The live birth rate per vitrified oocytes varies between 4.5% to 12% depending on the series. If there are at least 8 good quality or metaphase II oocytes at 36 years old, the chances of having a child are 62.1%, which is very good. Usually, the range of oocytes that it’s best to vitrify is between 9 and 15. Many patients do 1 stimulation cycle and have a very good number of oocytes. In some cases, it might be advised to do more than 1 cycle to accumulate more oocytes.
It is possible to do a double stimulation, which means that two stimulation cycles are done one after the other. Or it is possible to do one stimulation and repeat it 2 months later. In the lab, the embryologists will take a look at the follicular fluid aspirated during the oocyte retrieval, and they will check if the oocyte is of good quality and if they are in the metaphase II stage, which are the ones that will eventually be capable of being fertilized. They are introduced in different straws and cryopreserved with nitrogen banks. The quality of these eggs from that moment on doesn’t change.
Other questions often ask are: Does the cryopreservation impact the outcome of these oocytes? Is it safe for the oocyte? Will my children afterwards have no problem? The answer is no. There’s been a lot of controversy on this subject for a few years, but for many years already studies have shown that this is a very safe procedure.
The fact of having had your eggs cryopreserved for many years does not have an impact on the risk of embryo malformations.
At Eugin clinic, the program called time-freezing started in 2011, where over 1400 treatments have been done already, over 90% of women who vitrified their eggs are single, which means that most of them haven’t had a chance of naturally conceiving, and they want to preserve this option for the future.
In 2011, the mean age of patients who applied for this program was 40 years old, which is a bit old. Later on, the mean age for this procedure has been steadily declining, so nowadays, the mean age of our patients is less than 37 years old.
When we look the mean number of oocytes obtained per cycle has been steadily increasing, there are around 9 and 10 eggs obtained. The mean number of cycles per patient is 1.2, so that means that most of the patients have enough satisfactory results after just 1 cycle.
Around 53% of the women who came back to use their vitrified oocytes had a partner, so from the 90% that were single at the beginning, half of them already had a partner. The other 46% decided not to wait anymore. The mean age of transfer is 41 years old, and the mean age at vitrification was 38.6 years old, which means that most patients who are already using these oocytes are the ones who vitrified them later in life. The older the patient is, the faster they want to use the oocytes. Using the eggs of when you were 38 years old at 41 gives you already a huge advantage compared to all other women at 41 who try to conceive.
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