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 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.
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.
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.
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