Article Clinical embryology|Articles in Press

A comparison of the morphokinetic profiles of embryos developed from vitrified versus fresh oocytes

Published:February 28, 2023DOI:


      Research question

      Do morphokinetic profiles and treatment outcomes differ between embryos developed from vitrified or fresh oocytes?


      A retrospective, multicenter analysis, used data from eight CARE Fertility clinics across the UK between 2012 and 2019. Patients receiving treatment using embryos developed from vitrified oocytes (n = 118 women, n = 748 oocytes, providing 557 embryos) during this time period were recruited and matched with patients undergoing treatment with embryos developed from fresh oocytes (n = 123 women, n = 1110 oocytes, providing 539 embryos) in the same timeframe. Time-lapse microscopy was used to assess morphokinetic profiles, including: early cleavage divisions (2- through to 8-cell), post cleavage stages including time to start of compaction, time to morula, time to start blastulation and time to full blastocyst. Duration of key stages (hpi) such as the compaction stage were also calculated. Treatment outcomes were compared between the two groups (live birth rate, clinical pregnancy rate and implantation rate).


      A significant delay of 2-3 hours across all early cleavage divisions (2- through to 8-cell) and time to start of compaction occurred in the vitrified group versus fresh controls. The compaction stage was significantly shorter in vitrified oocytes (19.02±0.5 hours) compared to fresh controls (22.45±0.6 hours). Therefore, there was no difference in the time (hpi) that fresh and vitrified embryos reached the blastocyst stage (108.03±0.7 vs 107.78±0.6). No significant difference occurred for treatment outcomes between the two groups.


      Vitrification is a useful technique for extending female fertility with no effects on IVF treatment outcome.

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      Kathryn Montgomery holds an MRes Bioscience from Aberystwyth University, from which her research dissertation was conducted in collaboration with CARE Fertility, Manchester, resulting in this publication. Following the successful completion of her masters degree Kathryn is now an equine semen analysis technician for Stallion AI Services, UK.