Cleavage stage or blastocyst transfer: what are the benefits and harms?
Debate continues about the optimal day for embryo transfer--cleavage or blastocyst stage. There is a lack of good evidence about cumulative pregnancy outcomes after fresh and frozen-thawed transfers.
Volume 106, Issue 2, Pages 244-250
Authors:
Demian Glujovsky, M.D., M.Sc., Cynthia Farquhar, M.D., M.P.H.
Abstract:
ET is a critical step in an assisted reproduction cycle. Over the past decade there has been an increasing trend to extending culture from cleavage-stage to blastocyst transfer. There has also been a trend to single ET and reporting the success of an assisted reproductive cycle as a cumulative live-birth rate after using both fresh and frozen embryos. There is low evidence that fresh blastocyst transfer is associated with improved live-birth rates compared with fresh cleavage-stage embryos. However, in the few studies that report cumulative pregnancy rates after fresh and frozen transfers, no significant difference was found. Cleavage-stage transfer is associated with greater numbers of embryos available for freezing, and blastocyst transfer is associated with increased number of cycles with no embryos to transfer. Further well-designed studies are warranted to evaluate the outcomes for blastocyst transfer including cumulative live-birth rate after fresh and frozen transfers, time to live birth, costs of the different transfer strategies, and perinatal mortality and severe perinatal morbidity.
1 Comment
Drs. Glujovsky and Farquhar,
Thank you for the great review of cleavage vs blastocyst embryo transfer. It was a nice highlight of what we know, the weaknesses of what we know, and what we still need to know. You comment that the appropriate study design to address this question requires cumulative live birth per retrieval cycle, which I completely agree with. However, it is clearly difficult for us as researchers to wait even 7 months to change our outcome from clinical pregnancy to live birth, much less wait years down the line for cumulative birth data. I would love to hear your thoughts on the best way to encourage cumulative live birth reporting? We could certainly try to model that, based on what we know of outcomes of frozen embryos, but that would be limited by assumptions in the model. Do you think registries that allowed future reporting of RCTs would be ideal? Or perhaps allowing and encouraging authors to re-publish RCT data years down the line with cumulative results would be best? I would love your expert thoughts and insight!