Guide on fertility preservation for younger women

In this session, Dr Belén Marqueta, Gynaecologist, Specialist in Human Reproduction at Clínica Eugin, Barcelona, has been talking about the egg freezing process, when it is recommended and how to start. Social fertility preservation has become more and more popular, and several factors took place in the last half of the 20th century when women started to work outside their homes and good contraception methods appeared. These factors allow women to control their fertility, and they were able to decide when they want to get pregnant. From the biological point of view, the best age to get pregnant is between 18 and 30 years old, more or less. Unfortunately, this is the period when people usually develop their professional careers and their personal life, and this could drive a conflict of interest, and consequently, there will be a high percentage of women who voluntarily will delay motherhood. According to data from United Nations, in the last 4 years, the motherhood delay is generalized in North America and European countries, the mean age for the first birth in Europe in 2010 was 28.7 years. What is important to remember is that with age, there is a progressive decrease in the oocyte quantity and quality, and this means that a woman is going to have a lower ovarian reserve, it is a physiological ageing of the ovary.

Ovarian reserve testing

How can we test ovarian reserve? Two things have to be taken into account, the first one is the quality of the oocytes and the second is the quantity of the oocytes. There are no markers that can check the quality, but it is well known that age is going to decrease the quality of the oocytes. It is possible to assess the quantity of the oocytes through a blood test by doing an AMH (Anti-Müllerian hormone) test, and it is also possible to do a simple ultrasound to see how many antral follicles are there. From 30 years of age, fertility starts to decline slowly, and it’s getting to drop faster after 35 years and so on, it is going to get more difficult to get pregnant and also that there is going to be a higher risk of miscarriage related to maternal age. When we talk about oocyte quality, we refer to oocyte competence, which is mainly due to some chromosomal abnormalities that are going to appear in a woman’s eggs as her age increases These chromosomal abnormalities make it more difficult for the embryo to implant, and sometimes the embryos may fail to implant or cause miscarriage during the first semester of pregnancy.

Oocyte vitrification

Nowadays, the only way to preserve a woman’s fertility is oocyte verification. How does it work? The patient can start an ovarian stimulation treatment from the 2nd or the 3rd day of the cycle, it is performed with some hormones with subcutaneous punctures, and we ask the patients to come to do the follicular checks, we do these follicular checks with ultrasound, and also we do these follicular checks with blood tests. The follicles of the patient are monitored while they start growing depending on the response, and then the patient is asked to come for a second follicular check, usually, they need to have 3 or 4 follicular checks. When we see that all the follicles are big enough, more or less, we give them the last injection to induct the ovulation and this way, we know that 36 hours later, we can see our patient in the operation room and perform the egg retrieval.

Egg retrieval

Egg retrieval is always performed in the operating room, and it is always done under anaesthesia. Every follicle is punctured, and the liquid that is inside the follicles is taken into the laboratory where the embryologists select the eggs that are inside the liquid, and after that, the embryologists can perform the cryopreservation of the eggs in their laboratory. How many eggs do we recommend freezing? That always depends on the patient’s age. Each curve is going to show the probability of having at least 1 live birth at home, depending on the age of the patient and the number of mature oocytes obtained on the day of the follicular puncture. The best outcomes of this procedure are obtained when a woman freezes her eggs at a proper age.

Social freezing – studies & outcomes

At Eugin, the oocyte preservation program started in 2011, and since that time, more than 1 500 cycles were performed. The reason behind this is mostly due to lack of a partner at that moment in life, the second reason was because of their professional careers, and also some women manifested they had late childbearing. Studies performed at Eugin show that there is a significant decline in the mean age at the time of oocyte preservation. In 2011, the mean age was 40 years old, while in 2019, it was 37.2. The main factor to determine motherhood chances is the age of the oocyte. Women that undergo this kind of treatment have a better prognosis than the ones that performed this treatment 8 years ago. It’s probably because nowadays, there is more information available as well as more data and studies performed. Who returns to attempt to get pregnant with these vitrified oocytes? According to Eugin’s data, from 1 500 patients, there were 123 that have come to use their eggs and there were already 131 transfers performed. The returning rate is 8%, and the mean age at the moment of the cryopreservation was 38.5 years old, while the mean age at the time of transfer was more or less 41.5 years old. Almost 100% of those patients didn’t have a partner at the moment of performing cryopreservation. At the time of returning, more the half of them had a partner. What happens when you decide to use those vitrified eggs? The eggs are thawed in the lab, the survival rates are over 90%. After that, we can perform the fertilization of these eggs with partner or donor sperm depending on each case, and the fertilization rate is more or less 75%. Such embryos have similar pregnancy rates compared to those patients who use fresh oocytes. The pregnancy rates of the patients that come and use their eggs after freezing them show that the rates depend on the patient’s age, but it depends on the moment when the patient performs the cryopreservation, not the moment when the patient is performing the transfer. It’s important to do this kind of treatment as soon as possible, and it’s good to note that obstetric outcomes are similar to those of the general population.