Should I consider egg freezing if I want a family in the future? It’s a question that you or somebody close to you has probably asked themselves, with more and more women looking to preserve their fertility as they age. In fact, egg freezing is the fastest-growing fertility treatment in the UK – there were 11 times more egg freeze cycles in 2021 than in 2011.
Many women taking up the treatment may seem young – under the age of 30 – but the ovaries do age far quicker than the rest of our organs. Why exactly, isn’t clear. But the consequences of it are well understood: as ovaries age, there is a progressive loss of eggs that ultimately leads to menopause and infertility.
In addition to the number of eggs decreasing, the ‘quality’ of the eggs reduces as the ovaries age. Over time, there are more changes in the DNA, the genetic material, in the eggs. This leads to an increased rate of chromosomal abnormalities resulting in an increased rate of miscarriages, pregnancy complications and babies born with genetic conditions.
Therefore, egg freezing – also known as oocyte cryopreservation – is seen as a promising option to many. But how exactly does it work? How reliable is it? And what are the risks?
Egg freezing is a medical process that involves hormonal stimulation of the ovaries to overproduce eggs. These eggs are then retrieved during a procedure where a healthcare professional accesses the ovaries by passing a needle through the vagina and out into the pelvis under ultrasound guidance. Most women 38 years or younger will have around 7-14 eggs collected, but those with a lower ovarian reserve will produce fewer eggs for collection.
Eggs are then collected from the ovaries and the viable ones are frozen and stored until needed. This is when a woman wants to proceed to the next stage where the egg is fertilised in a lab via in vitro fertilisation (IVF). Then one, or multiple, viable embryos are implanted back into the woman’s womb to further develop – hopefully to a full pregnancy.
There is much research and development, and testing and trialling of different methods in multiple parts of the process, to deliver the best results.
For example, the egg-freezing process can be slow, or fast – which is known as flash freezing. The latter approach has been shown to increase egg survival and improve pregnancy rates. Flash freezing, also known as vitrification, aims to first fortify the eggs with a cryoprotectant, then ‘ultra-rapidly’ cool them in an effort to solidify the cell and avoid the formation of ice crystals.
With assisted reproductive technologies, nothing is guaranteed, and egg freezing is no different. Using data from women mainly under 30, it’s estimated that the survival of eggs after vitrification and thawing is 90-97 per cent, the fertilisation rate is 71-79 per cent and the implantation rate is 17-41 per cent. The overall pregnancy rate per vitrified and thawed oocyte is as low as 4.5-12 per cent.
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It should also be noted that egg freezing and consequent IVF do present challenges. Some key considerations include the risk to women regarding hyperstimulation of the ovaries, carrying a pregnancy at an older age, and risk to the offspring – such as reported lower birthweight, intrauterine growth restriction, and a possible increased risk of congenital abnormalities.
One of the highest medical risks can be caused by the hormone medication-induced hyperstimulation of the ovaries. This can lead to ovarian hyperstimulation syndrome, bringing about a shift in fluid out of blood vessels and into the ‘third space’ where fluid should not normally accumulate in the body.
The syndrome can be life-threatening in approximately 0.1-3 per cent of patients who experience the severe form, which causes blood clots, shortness of breath, abdominal pain, dehydration and vomiting that necessitates hospital admission. There is the more common mild-to-moderate syndrome involving fatigue, nausea, headaches and abdominal pain. All women undergoing ovarian hyperstimulation need to be closely monitored for the syndrome.
These are the biggest risks related to egg freezing, but there are also big questions related to the treatment that likewise deserve our attention. For instance, is it right to emphasise genetically related children as the only way to grow a family? Does egg freezing put further reproductive responsibility on women?
While answers to these questions may differ person-to-person, we can all agree that egg freezing is a technological feat that’s enabled many women to become pregnant in situations when previously it would have been impossible. And now the science is here, we need to properly evaluate the potential risks and consequences.