The mtDNA of mature oocytes is evenly split throughout cell divisions up until the blastocyst stage, after which mtDNA replication starts. Recent studies assessed the mtDNA copy number (mitoscore) of blastocysts as a parameter for embryo viability. However, conflicting and limited results are available for cleavage stage embryos. Currently, there is still a gap in the data linking the cleavage stage mitochondrial function with the ploidy state and the developmental kinetics. The aim was to evaluate whether the mitoscore of cleavage stage embryos is correlated with the ploidy state and the developmental kinetics up to the blastocyst stage.