Effect of micro-environment maintenance on embryo culture after in-vitro fertilization: comparison of top-load mini incubator and conventional front-load incubator

Purpose: To investigate the effect of microenvironment maintenance on embryo culture and clinical results using two types of incubators. Methods: Temperature and oxygen concentration in a mini-incubator and a conventional incubator were compared following a 5-s door opening/closing procedure. Embryos of 30 in-vitro fertilization embryo transfer (IVF-ET) cases were randomly allocated to either one of the incubator, cultured, and the early-stage good embryo formation rate and the good blastocyst formation rate were compared, as indicators for micro-environment maintenance ability. Results: Temperature recovery after a 5-s door opening/closing procedure was approximately 5 min for the mini-incubator and 30 min for the conventional incubator. The oxygen concentration return was significantly improved in the mini-incubator (3.0 ± 0 min) compared with the conventional incubator (7.8 ± 0.9 min). Both the early-stage good embryo formation rate and the good blastocyst formation rate were significantly higher in the mini-incubator (39.5% and 15.1%) than the conventional incubator (28.4% and 7.8%). Conclusion: The microenvironment maintenance ability of incubators appears to significantly influence the formation of good embryos.