Egg freezing, the process by which eggs are removed and cryogenically stored to prevent age-related decline, has seen a rise in popularity, with a threefold increase since 2014, according to research from the London Women’s Clinic. Meanwhile, recent coverage of “social” egg-freezing advocates, such as Dr Emily Grossman, seems to offer hope to women who want to buy time before meeting the right partner or to delay pregnancy. Ostensibly, egg freezing offers women this breathing space: to preserve their chance of having a baby without compromising on other aspects of their lives.

Except the most recent figures tell a different story. A study by the Human Fertilisation and Embryology Authority (HFEA) of women who used their frozen eggs in 2014 found that only 14% of implantation cycles were successful. So how effective is the technology? And should women really be trusting egg freezing as a fertility solution, given the limited evidence in its favour? Dr Kylie Baldwin, a medical sociologist with the Centre for Reproduction Research at De Montfort University, is sceptical: “The technology has been presented as a magic bullet to level the playing field between women and men, reproductively speaking. However, the success rates are still low.”

The science is relatively straightforward. As Dr Simon Fishel, head of research and development at Care, a UK fertility clinic, explains, patients are injected with drugs to stimulate the ovaries for around 10 days. The eggs are then removed before being taken away to be frozen and stored in a lab. The freezing process has got more effective in recent years: it used to take more than four hours, but now it is done in a matter of minutes by a technique called vitrification, which Fishel deems “much more efficient”. He believes egg freezing is now “as good as IVF” – although that has a success rate of 26.5%, according to data from HFEA.

Dr Zeynep Gurtin, a senior research associate at the London Women’s Clinic, is – like Fishel – optimistic. “Vitrification has significantly increased the survival rates of frozen-thawed eggs, resulting in much better rates of fertilisation.” However, she feels it will be “some time before these potential successes are reflected in national and clinical statistics”. And, even if egg freezing itself is improving, current patients may still face issues – particularly if they are over the optimum fertility age. “It’s all about the egg and the age of the woman from whom the eggs were taken,” says Fishel. Egg freezing may pause the ageing process, but it can’t reverse it.

Ebryos being prepared for instant freezing using the vitrification process. Photograph: Ben Birchall/PA

Brigitte Adams, 45, who froze her eggs aged 39, learned this the hard way. “When I froze my eggs, it was empowering; I hadn’t met anyone and I wanted to wait for a partner to have a child with. When I produced 11 eggs, my doctor said, ‘Congratulations,’” – and that was that. When she subsequently went to defrost her eggs, only one survived to the point where it could be implanted – and, although she fell pregnant, she miscarried weeks later. “It had never occurred to me that it wouldn’t work. That was it: my last possibility of having a biological child.”

Adams feels she wasn’t given enough information. She wishes she had been advised to do multiple cycles – Fishel recommends at least 20 eggs for the optimum chance of success – repeating the process over two or three cycles, especially for those beyond their mid-30s. She also regrets waiting: “I wish I had gone into it earlier, with more information and a better grasp on reality.”

The obvious answer might be to freeze eggs at an earlier age. But in the UK, the HFEA places a 10-year limit on storage. “I don’t think many women younger than 30 will consider freezing their eggs under the current regulations,” says Gurtin. And even without regulation, the huge cost of egg freezing – around £10,000 in the UK – is a considerable barrier for most. Although egg freezing can be covered by insurance on medical grounds (cancer for instance), for “social” purposes it must be done privately.

Adams believes all this requires a “clearer conversation” – one that accommodates the substantial possibility of failure and therefore allows women to manage risks – for instance, with multiple cycles. “We read a lot about women freezing their eggs, but that’s only one half of the story: the first half, where there is still hope and optimism.”

She also believes that media coverage of company-funded egg freezing (for example by US companies such as Apple and Facebook) “glosses over the fact it is still a cutting-edge medical procedure and it’s not going to work for everyone”.

Baldwin argues that responsibility also rests with clinics to report data accurately. “Many studies that give favourable odds of success are drawn from highly specialised clinics working with eggs much younger than the average user of egg freezing. Clinics need to be honest about how likely it is that they will be able to replicate these results in their own labs.”

Then again, the simple truth echoed by most experts is that there just isn’t enough evidence on egg freezing to know one way or another. “As the numbers of women undergoing egg freezing are much smaller than the numbers undergoing IVF, it will take some time until any meaningful data can be amassed,” says Baldwin. Ultimately, until scientists establish exactly how effective egg freezing is, the narrative should perhaps shift from one of empowerment to a more cautious approach, taking into account the fallibility of the process and acknowledging that, in Brigitte’s words: “It might be your plan B, but you will need a plan C as well.”