18 July 2024: Britain’s largest ever study of egg freezing which followed up the outcome of almost 30,000 eggs frozen at the London Women’s Clinic shows that success rates are comparable to those achieved by routine IVF and subject to the same variables of female age and embryo quality. (1) When seen alongside other similar large-scale egg-freezing studies from other countries, the results of this study add to a pattern of success which is consistent, predictable and reliable.
The study, published today in the peer-reviewed journal Reproductive Biomedicine Online , analysed the outcomes of treatment for 299 patients who had frozen their eggs between 2008 and 2022 and returned to thaw them for fertilisation and pregnancy. The results of this 15-year study found an overall live birth rate per embryo transfer of 26% which varied according to the age at which the eggs were frozen, with a lower rate in over-35s but only 5% in over-40s.
The cumulative live birth rate after the transfer of all embryos created from the thawed eggs was 34%, rising to 45% in those who had frozen their eggs before the age of 36.
‘These are results comparable with those nationally recorded in routine IVF,’ said Professor Nick Macklon, senior author of the study and Medical Director of the London Women’s Clinic. ‘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.’ (2)
What has this and other studies told us so far:
‘These are encouraging results for those considering freezing their eggs for future use,’ said Professor Macklon. ‘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.’
The results also challenge the sceptical perception of egg freezing, which may arise from dated studies. The UK regulator, the Human Fertilisation and Embryology Authority (HFEA), for example, recently warned that ‘when looking at success rates for frozen eggs, numbers tend to be quite low’. However, the results from this large study reflect outcomes which are robustly recorded and analysed, and comparable with those of fresh single embryo transfers in IVF when age and egg quality and quantity are taken into account.
‘It thus seems reasonable to conclude,’ said Professor Macklon, ‘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. 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.’
Notes
* RBM Online, founded by Professor Sir Robert Edwards in 2000, is a monthly peer-reviewed journal covering the full range of human reproductive health and disease, including basic and translational science, embryology, ART, infertility, male reproduction, periconception and pregnancy, reproductive health and the social implications of fertility care.
* For more information on this press release and the published paper, please contact:
Duncan Nicholas, RBM Online Development Editor
dev.editor@rbmonline.com
https://linktr.ee/rbmo
Reproductive BioMedicine Online
Experimental study
Human embryos
Clinical outcomes of vitrified-warmed autologous oocyte cycles with 15-year follow-up at a single UK centre: consistent and predictable results
18-Jul-2024
The authors report no financial or commercial conflicts of interest.