During pregnancy, there is increased expression of some cytokines at the fetal–maternal interface; and the clarification of their roles in trophoblast–endometrium interactions is crucial to understanding the mechanism of placentation. This review addresses the up-to-date reported mechanisms by which the members of the transforming growth factor beta superfamily regulate trophoblast proliferation, differentiation, and invasion of the decidua, which are the main phases of placentation. The available information shows that these cytokines regulate placentation in somehow a synergistic and an antagonistic manner; and that dysregulation of their levels can lead to aberrant placentation. Nevertheless, prospective studies are needed to reconcile some conflicting reports; and identify some unknown mediators involved in the actions of these cytokines before their detailed mechanistic regulation of human placentation could be fully characterized.

Summary sentence

The TGF beta superfamily are expressed in the placenta, and regulate the process of placentation through the activation of several signaling pathways.