An analysis of spontaneous hatching in a human endometrial epithelial coculture system: Is assisted hatching justified?

Purpose: To evaluate spontaneous embryo hatching in an endometrial epitheli al coculture system, and compare it with cases where coculture was performe d because of maternal age, previous repeated implantation failures, or both . To clarify in which cases assisted hatching would be appropriate. Methods: Individual human embryos were cocultured on an endometrial epithel ial cell monolayer until Day 6. Results: Blastocyst hatching rate at Day 6, depending on maternal age was 9 .1% (age < 37 years) and 3.4% (age greater than or equal to 37 years). Howe ver; blastocyst hatching rates depending on number of previous IVF failures were similar. Conclusions: Maternal age and previous implantation failures are factors af fecting the ability of human embryos to reach the blastocyst stage in cocul ture. However, assisted hatching is,lot justified in these populations beca use of the absence of hatching rate differences between blastocysts obtaine d from these two groups and die control group.