For whom the egg thaws: insights from an analysis of 10 years of frozen egg thaw data from two UK clinics, 2008–2017
To better understand the characteristics of patients who returned to thaw their frozen eggs to attempt conception and their outcomes.
A retrospective analysis of clinical records for all own egg thaw patients in two UK fertility clinics across 10 years, 2008–2017.
There were 129 patients who returned to thaw their eggs, of which 46 had originally frozen their eggs for social reasons and 83 for a variety of clinical, incidental, and ethical reasons (which we have called “non-social”). Women who had frozen their eggs for social reasons were single at time of freeze, with an average age of 37.7. They kept their eggs in storage for just under 5 years, returning to use them at the average age of 42.5. 43.5% were single at time of thaw, and 47.8% used donor sperm to fertilise their eggs. Women whose eggs were frozen for non-social reasons were almost all (97.6%) in a relationship at both time of freeze and thaw. They had an average age of 37.2 at first freeze and 37.6 at thaw, having kept their eggs in storage for an average of 0.4 years. Overall, there was a 20.9% success rate among women attempting conception with frozen-thawed eggs.
Despite widespread assumptions, many women attempting conception with thawed eggs had not initially frozen them for social reasons. Women who froze their eggs for social reasons presented distinctly and statistically different characteristics at both time of freeze and thaw to women whose eggs were frozen for non-social reasons.
KeywordsEgg freezing Cryopreservation Fertility preservation Egg thaw Sociology Ethics
The authors gratefully acknowledge the clinical work undertaken by a large team of clinicians, nurses, and embryologists that has enabled this data analysis to occur. We appreciate the suggestions made by Professor Susan Golombok on earlier drafts and are thankful to Elena Linara-Demakakou for her help with the statistical analyses. We would also like to thank the editor of JARG and the anonymous reviewers for their helpful comments during the peer review process.
ZG—designed concept and analysis; collected and analysed data; and wrote the paper.
LM—developed database and analysed data.
DO—helped with initial stage of data collection.
JW—provided access to data, as head of lab from which data were gathered.
KA—helped in concept design; provided overview; head of clinic from which data was gathered.
There was no independent funding received for the study.
Compliance with ethical standards
Conflict of interest
There is no financial or commercial conflict of interest. During the period of research, all authors were working in the clinic from which the data was obtained, although some have now moved to other institutions.
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