A review of human studies indicates that the miR-520h is considered a pregnancy-associated biomarker detected in maternal plasma and highly expressed in serum during pregnancy [Silva et al. DOI:10.1016/J.Fsigen.2014.09.002]. An experimental study in human cord blood hematopoietic stem cells from twins demonstrated that the miR-520h showed high differences in expression in both fraternal and identical twins and was placed in a group where environmental factors had a more significant effect than genetics [Ajami et al. DOI:10.22074/cellj.2019.5683].