Humid versus dry incubator: a prospective, randomized, controlled trial

Humidified embryo culture improved the ongoing pregnancy rate as compared with a dry environment.

Volume 108, Issue 2, Pages 277–283


Mohamed Fawzy, M.D., Mohamed Y. AbdelRahman, M.D., Mohamed H. Zidan, M.Sc., Faten F. Abdel Hafez, M.D., Hazem Abdelghafar, M.D., Hesham Al-Inany, M.D., Ph.D., Mohamed A. Bedaiwy, M.D., Ph.D.



To evaluate the efficacy of a dry versus humidified incubator on human embryo development ex vivo.


Prospective, double-blind, randomized, controlled trial.


Private fertility centers.


A total of 297 women undergoing in vitro fertilization randomized into two groups.


From days 0 to day 5 or 6 of culture, intervention group embryos exposed to dry culture and control group embryos exposed to humidified culture.

Main Outcome Measure(s)

Subsequent ongoing pregnancy rate.


After transfer of embryos, there were statistically significantly lower rates of clinical and ongoing pregnancy in the dry culture arm than in the humidified culture arm (odds ratio [OR] 0.57; 95% confidence interval [CI], 0.36–0.91; versus OR 0.54; 95% CI, 0.34–0.85). On day 3 of culture, embryo quality and compaction were lower in the dry culture group (OR 0.38; 95% CI, 0.32–0.45) than in the group exposed to humidified culture (OR 0.23; 95% CI, 0.19–0.27). On day 5 of culture, embryos in dry culture had a lower rate of blastocyst formation (OR 0.39; 95% CI, 0.33–0.46), quality (OR 0.34; 95% CI, 0.29–0.40), and cryopreservation (OR 0.41; 95% CI, 0.35–0.48).


In this study, human embryos cultivated ex vivo in a dry incubator had statistically significantly decreased implantation and clinical and ongoing pregnancy rates. Our findings indicate the need for larger multicenter, randomized, controlled trials.

Clinical Trial Registration Number


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Go to the profile of Jason Franasiak
over 5 years ago

Thank you for this very interesting and well done randomized controlled trial which evaluates culture conditions. It appears the findings strongly support. As noted in your manuscript, it appears as though the osmolality of the media changed despite oil overlay in the non-humid conditions. Are there other possible mechanism which could be impacted? Is there any thought that there might be an optimal humidity range for culture (rather than humid versus not) as an area for further study?

Go to the profile of Mohamed Fawzy
over 5 years ago

Jason, thank you for your comment. The other possible mechanisms may include a role for humidity to facilitate gases exchange and hence the micro environment stability. However, these are assumptions to be examined. The optimal humidity level is to be also specified. However, there is data from David McCulloh to subbort better clinical outcomes post IVF when the humidity increased to 99% compared to lower levels than 85%.