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

Objective To evaluate the efficacy of a dry versus humidified incubator on human embryo development ex vivo. Design Prospective, double-blind, randomized, controlled trial. Setting Private fertility centers. Patient(s) A total of 297 women undergoing in vitro fertilization randomized into two groups. Intervention(s) 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. Result(s) 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). Conclusion(s) 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 NCT01695096.