Evaluation of the safety of time-lapse observations for human embryos

To assess the effects of light from an integrated optical microscope and evaluate the safety of time-lapse observations using a built-in microscope incubator. We prospectively compared the fertilization rate and embryonic morphology after intracytoplasmic sperm injection between embryos cultured with time-lapse observations every 15 min in an incubator with an integrated optical microscope and embryos with intermittent observations (once a day) in conventional incubators. No significant differences were observed in the fertilization rate (57.5% vs. 57.5%) or the rate of excellent-good cleavage embryos (36.0% vs. 36.0%). These results suggest that time-lapse observations using an incubator with an integrated optical microscope may therefore be safely utilized in clinical practice.