To evaluate whether there is a correlation between the increase in mitochondrial DNA (mtDNA) content observed in post-warming human blastocysts, their redox state and their mitochondrial mass measured by confocal and electron microscopy, respectively. A prospective cohort study was carried out with a total of 17 aneuploid blastocysts. To calculate the redox ratio, NADH and FAD autofluorescence quantification was performed with 10 of them, 5 blastocysts cultured 5 hours after warming and other 5 blastocysts cultured a maximum of 1 hour after warming. Moreover, an electronic microscopy analysis of 7 blastocysts was performed, 3 of them cultured 5 hours after warming and another 4 cultured a maximum of 1 hour after warming by visual count of mitochondria. The statistical study for both experiments was conducted by correlation analysis and T-test. No significant differences (P>0.05) were observed regarding the redox ratio between just-warmed blastocysts (average redox ratio= 1.49) and blastocysts recovering after warming (average redox ratio= 1.26). Regarding the mitochondrial mass, no significant differences (P> 0.05) in the number of mitochondria were observed (just-warmed average mitochondria per cell= 30.77 vs recovering-after-warming average mitochondria per cell= 30.94). Furthermore, we do not observe differences in the mitochondrial matrix configuration that could indicate differences at the level of mitochondrial activity between the two groups. Despite the increase in mtDNA content observed after the stressful vitrification-warming process in human blastocysts (Pérez-Sánchez, ESHRE 2019), no consequential increase in redox activity or mitochondrial mass is observed.