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What is Egg Freezing?

Egg freezing is a revolutionary technology that allows mature eggs to be frozen and stored for later use. Initially developed as a means to ‘preserve’ the fertility of women undergoing medical procedures, such as cancer treatment, it is now increasingly used by women wishing to protect their fertility for a variety of ‘social’ reasons. Since we know that a woman’s fertility – including her ovarian reserve and egg quality – declines with age, egg freezing offers one option to those wishing to conceive later.

While sperm cells have been frozen, thawed and successfully used in fertility treatment for over five decades, the freezing of egg cells has a much shorter history. As the largest cell in the human body, with high water content, egg cells are difficult to manipulate; therefore, the older techniques of egg freezing – so called ‘slow freezing – although used since the 1980s, yielded low success rates. So it was only with the recent development of a new rapid freezing technique - called ‘oocyte vitrification’ (literally meaning ‘converting eggs to glass’) - that the possibility of freezing, storing and thawing viable eggs became a large-scale possibility.  

The first baby conceived using a ‘vitrified’ egg was born in 2010. In 2012, the American Society of Reproductive Medicine (ASRM), one of the world’s leading fertility organisations, lifted the ‘experimental’ label from egg freezing, citing studies that showed good thawing, fertilization, implantation, and live birth rates from vitrified eggs. This was followed in 2014 with Apple and Facebook’s announcements that they would cover egg freezing for their employees, catapulting discussions around egg freezing into the popular media.  

A cycle of egg freezing involves ovarian stimulation (using hormone based drugs to encourage the growth of an optimal number of eggs) and egg collection (under sedation), exactly the same as an IVF cycle. However, unlike in an IVF cycle, once the eggs are collected, instead of being fertilized in the lab, they will be flash frozen and stored for future use. When a woman who has frozen eggs wishes to have a baby, her frozen eggs will be thawed, fertilized in the lab using ICSI (intracytoplasmic sperm injection), and the resulting embryo will be transferred to her uterus. A woman’s age at the time of egg freezing is an important consideration and directly impacts the success rates of future IVF cycles using frozen eggs. The overall clinical experience has been that success rates with frozen eggs decline with maternal age (at time of egg collection) as do success rates with fresh eggs.

Egg freezing information sheet PDF
Download our information sheet about egg freezing

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