Indicating, for the first time, that it is possible to induce the embryonic diapause (ED) in blastosycyst of non-diapausing mammalian species and that such induction is fully reversible. Lambs were born from ovine blastocysts in which the ED was experimentally induced. It implies that ED is phylogenetically conserved phenomenon and not secondarily acquired by embryos and questions the current model of independent evolution of ED in different mammalian orders. Therefore, it provides a starting point to verify the flexible occurrence of ED in mammals and opens new perspectives for reproductive and evolutionary biology. If diapause does occur in all mammals (as we postulate), this may have huge implications for human pregnancy