A BBC television documentary about egg freezing prompted a flurry of media reports that the ‘true’ rate of success from this increasingly popular treatment lay hidden behind a smokescreen of misleading numbers and false claims. While the BBC conclusions were the result of a small survey and scrutiny of clinic websites, the reality is that scientific studies of egg freezing are quite transparent in their results, indicating that success rates are quite similar to other fertility treatments, such as IVF, and subject to the same factors in determining success in the delivery of a healthy baby.

One such study has just been completed at the London Women’s Clinic, where an ever-escalating number of women are opting for egg freezing and whose results suggest that the latest official figures released by the UK’s regulator the HFEA (for 2021) are running behind the reality of everyday progress. While the HFEA described egg freezing as ‘one of the fastest growing fertility treatments in the UK’, its caveat that ‘very few patients come back to use their eggs’, or that success is unusual, is not reflected in the latest study data. Indeed, our latest results, based on analysis of egg freezing outcomes over the past 15 years, appear to support other important international studies showing that the viability of frozen eggs is comparable to that found with fresh eggs, and that freezing and thawing have negligible impact on outcome. Pooling these latest LWC results with those from the international studies indicates, first, a consistency in outcome from treatment, and that the likelihood of a live birth from egg freezing is dependent on the same predictive factors evident in routine IVF. There is no smokescreen surrounding these results, no lack of transparency; these are non-biased results subject to rigorous scientific analysis, not the unsubstantiated claims of a survey or ill-informed individuals.

The first conclusion drawn from the LWC study - which involved the treatment outcomes of 299 patients returning to thaw and use their eggs for pregnancy - is that only a relatively small proportion of egg freezers do actually return to use their eggs. In our study, following up patients who froze their eggs between 2008 and 2022, the return rate was just 14%, a proportion similar to that found in other studies. To this extent, the HFEA was correct to warn that relatively few patients do actually return to use their eggs for pregnancy, but was incorrect to say that live birth success is ‘unusual’. Over the 15 years of the LWC analysis a total of 93 clinical pregnancies, resulting in 77 healthy births, were recorded from the cohort of 299 women returning to thaw their eggs. These are results comparable with routine IVF and dependent on the same predictive factors, notably female age at the time of freezing. Thus, according to freeze age, live birth rate per embryo transferred was 26% in women 35 and under, 20% among 35-39s, and 5% in those 40 and over.

Yet MP Miriam Cates, jumping on the BBC bandwagon, told the Mail on Sunday that women who freeze their eggs are relying on false promises, that egg freezing ‘doesn’t work’ and that only a ‘tiny percentage’ of people freezing their eggs will ever become pregnant. Such claims have no basis in scientific fact and seem as ‘false’ as the very accusations she is making. Indeed, results from our own and the large population studies recorded officially in the USA, Belgium and Australia are consistent and reproducible, giving them a stamp of reliability and accuracy for all to see.

So where are the ‘false promises’? What these studies first indicate is that the predictors of success in egg freezing are no different from those of other fertility treatments - and thus dependent on the age of the egg, the reproductive history of the patient, her ovarian reserve, and the number of eggs collected. So depending on these (and other) factors, it is reasonable for clinics to make efforts to predict the clinical outcome for their individual egg freezers.

At the LWC such predictions may also be more accurately made after analysis of its own substantial patient data. Patient numbers at LWC, which is Britain’s leading centre for egg freezing services, are sufficiently large for the application of sophisticated data analytics in calculating the outcome of treatment via a statistical model which incorporates individual patient characteristics and diagnoses. For example, certain clinical factors such as body mass index may have a profound effect on these estimates of success. Similarly, outcome may be affected by the number of eggs collected, which in most studies tends to peak at around 15 eggs. These are considerations evident in all fertility treatments, where ultimate ‘success’ (live birth) will depend on each step of the treatment cycle: fertilisation, embryo development, blastocyst formation, embryo transfer and implantation in the uterus. Analysis of all these factors may increase the reliability of forecasting outcome and calculate the personal probability of having a baby for each egg freezing patient at the LWC.

Of course, egg freezing offers no greater guarantee of a baby than any other fertility treatment. Overall and irrespective of age, around one three first treatment cycles will conclude successfully; estimates of probability tend to increase with additional treatments. And the latest LWC study of egg freezing adds one further boost to the odds, especially in that most challenging patient group of ‘older’ women. Results in this age group were improved when the fertilised eggs of women who froze their eggs at the age of 40 and over were genetically tested for any chromosome abnormality, a technique known as PGT-A. PGT-A for embryo selection appeared to double the birth rate in a first attempt when compared to results with an untested embryo (40% against 21%).

What we can say with certainty is that not everyone who returns to thaw and use their eggs will have a baby, nor will everyone who freezes eggs return to use them. Indeed, most women will freeze in the hope of not needing to use them. But for many patients who choose to defer their pregnancy for another day egg freezing can provide reproducible and reassuring results. And these are results which are based on scientific fact, not on small surveys and unsubstantiated claims.

Contact the London Women's Clinic on 020 7563 4309 to find out more on elective egg freezing or by completing the contact form on our website.