Impact of post-warming culture duration on clinical outcomes of vitrified good-quality blastocyst transfers: a prospective randomized study

Implantation rate during FET cycles were not different whatever the duration of post-warming culture of good-quality blastocysts. Warming blastocysts on the day before could enable an adaptation of transfer strategy.

Volume 110, Issue 7, Pages 1290–1297


Charlène Herbemont, Pharm.D., Sarah Chekroune, Pharm.D., Sarah Bonan, M.D., Isabelle Cedrin-Durnerin, M.D., Alexandre Vivot, M.D., Charlotte Sonigo, M.D., Jeremy Boujenah, M.D., Michael Grynberg, M.D., Ph.D., Christophe Sifer, M.D.



To determine whether post-warming culture duration (1 hour vs. 18 hours) influences implantation rates (IRs) of good-quality blastocysts (GQB) in a good-prognosis population.


Prospective interventional randomized study.


University hospital.


One hundred sixty-two GQB transfers.


Patients’ vitrified blastocysts were randomly allocated to group A, warming on the day before transfer (n = 81), or B, warming on the day of transfer (n = 81).

Main Outcome Measure(s)

IR, live birth rate, reexpansion degree, and quality after warming and immediately before transfer.


Quality of the warmed and transferred blastocysts was similar (respectively, 39.1% and 32.7% top quality [≥B4AA/AB/BA] in group A vs. 41.7 and 42.2% in group B). In group A, 14 of 102 blastocysts (12.2%) appeared to be unsuitable for transfer, versus only 1 of 103 (0.9%) in group B, thus leading to an additional warming. As expected, reexpansion degree just before transfer was higher in group A (0.90 vs. 0.70). Likewise, the proportion of hatched blastocysts before transfer was higher after a longer culture period (38.6% in group A vs. 12.7% in group B). IRs were similar (38.0% in group A vs. 36% in group B), as were live birth rates (35.8% in group A vs. 34.6% in group B).


IRs were not different, whatever the duration of post-warming culture of GQB. Both warming strategies could be applied to good-prognosis patients to optimize the laboratory workflow without any detrimental effect.

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