Laser-assisted hatching zona thinning does not improve the pregnancy outcomes of poor-quality blastocysts in frozen-thawed embryo transfer cycle: a retrospective cohort study.

It had been suggested, after facilitating the hatching process, improved pregnancy outcomes could be attained in embryos with thick and hard zona. This study aimed to determine the effect of zona thinning on pregnancy outcomes in poor-quality frozen-thawed blastocysts. This retrospective study included 230 women (≤ 40 years) who underwent frozen embryo transfer of poor-quality blastocysts (scored   0.05; multivariate, OR = 0.652, P > 0.05), and the area under the receiver operating characteristic curve of the regression model was almost 0.7. It suggested that zona thinning may not be supposed to perform on poor-quality, frozen-thawed blastocysts. The indications of assisted hatching were still needed to further investigate.