Endocrine and paracrine mechanisms in human placenta and fetal membranes in preterm birth

Human placenta and fetal membranes are unique tissues, genetically originated from the fetus and physiologically engaged as mediators of the maternal-fetal dialog. They produce a huge number of signaling substances including cytokines, neuropeptides, steroids and amines. These are released into the amniotic fluid, or act on the adjacent tissues, and thereby are able to modulate myometrial contractility and cervical ripening in a paracrine fashion.2 As a result, placenta and membranes are putatively involved in both physiological and pathological mechanisms leading to the initiation of labor. The placental and fetal membranes hormones play an important role in human parturition by: (i) endocrine mechanisms, with increasing secretion of placental hormones, and (ii) paracrine mechanisms activation, characterized by local inflammation, myometrial contractility and cervical ripening. © 2007 Informa UK Ltd.