UK study shatters myths on egg freezing success
A landmark British study spanning 15 years has demonstrated that egg freezing success rates are comparable to routine IVF, offering reassurance to women considering this fertility preservation option.
Professor Nick Macklon, senior author of the study and Medical Director of the London Women’s Clinic
Egg freezing success rates comparable to IVF
Britain’s largest ever study on egg freezing has yielded encouraging results for women considering this fertility preservation technique. The research, conducted at the London Women’s Clinic, analysed the outcomes of nearly 30,000 frozen eggs over a 15-year period. The findings, published in the journal Reproductive Biomedicine Online [1], reveal that success rates for egg freezing are on par with those achieved by routine IVF and are subject to the same variables of female age and embryo quality.
The study followed 299 patients who had frozen their eggs between 2008 and 2022 and subsequently returned to thaw them for fertilisation and pregnancy. The overall live birth rate per embryo transfer was found to be 26%, with variations based on the age at which the eggs were frozen. Notably, the cumulative live birth rate after the transfer of all embryos created from thawed eggs was 34%, rising to an impressive 45% in women who had frozen their eggs before the age of 36.
Professor Nick Macklon, senior author of the study and Medical Director of the London Women’s Clinic, emphasised the significance of these results: “These are results comparable with those nationally recorded in routine IVF. The results are also comparable with those reported from other similar studies in the USA, suggesting that the doubts still commonly expressed about the reliability of egg freezing are misplaced. Taken together, the results appear consistent, predictable and reassuring.”
Growing demand for egg freezing
The study highlights a significant increase in the number of women seeking egg freezing treatment for personal reasons. At the London Women’s Clinic, annual patient numbers rose from 150 women in 2015 to more than 800 in 2022. This trend aligns with national statistics reported by the Human Fertilisation and Embryology Authority (HFEA), which describe egg and embryo storage cycles as “the fastest growing fertility treatments in the UK”.
Despite the growing interest, the number of women returning to thaw their frozen eggs remains relatively low. The study found that only 14% of patients who had frozen their eggs returned to use them, a rate similar to that observed in other studies.
Age and embryo quality remain crucial factors
As with traditional IVF, the success of egg freezing is heavily influenced by the age at which eggs are frozen and the quality of the resulting embryos. The study revealed that women who froze their eggs before the age of 35 had a cumulative live birth rate of 57%, significantly higher than the overall rate.
The research also demonstrated the potential benefits of genetic screening for chromosome abnormalities (PGT-A) in frozen embryos. Across all age groups, the use of PGT-A was associated with a live birth rate double that found with untested embryos (40% vs 21%). Notably, all live births in women aged 40 or over were from embryos that had been screened as chromosomally normal.
Challenging perceptions and managing expectations
The results of this comprehensive study challenge some of the scepticism surrounding egg freezing, which may have been based on outdated information. Prof. Macklon noted: “It thus seems reasonable to conclude that based on these results and those of other studies, egg freezing and thawing can provide a very real opportunity for women to achieve pregnancy and live birth at a time of their choosing.”
He added: “With consistency in results, patient expectations can be managed similarly to all IVF treatments. An assessment of age and embryo quality can help estimate the potential outcomes of treatment.”
Implications for future fertility choices
This research provides valuable insights for women considering egg freezing as a means of preserving their fertility. The study found that the mean age at which patients froze their eggs was 37.6 years, with an average storage period of 24 months before returning to use them at an average age of 40 years.
Prof. Macklon commented on the implications of these findings: “Current consensus based on these and other results would be that 10 to 15% of patients who originally froze their eggs in their later thirties will return to thaw and use them when they are, on average, between 40 and 42 years old.”
As egg freezing technology continues to advance and more long-term data becomes available, women and healthcare providers alike will be better equipped to make informed decisions about fertility preservation options. This study marks a significant step forward in understanding the potential of egg freezing and its role in modern reproductive medicine.
Reference:
- Shah, T., Garratt, J., Mclaughlin, A., et al. (2024). Clinical outcomes of vitrified-warmed autologous oocyte cycles with 15-year follow-up at a single UK centre: consistent and predictable results. Reproductive Biomedicine Online.
https://doi.org/10.1016/j.rbmo.2024.104376
