Fetal membranes: degenerative or functional tissues?

The fetal membranes, consisting of amnion and chorion, cover approximately 70% of the uterine cavity. Accumulating evidence indicates that the fetal membranes are not mere degenerating tissues covering the amniotic fluid and the fetus, but one of the most important functional tissues during pregnancy. The fetal membranes not only protect the fetus, but also secrets a series of hormones and cytokines involved in pregnancy maintenance and fetal development as well as the initiation of labor. Early activation of fetal membranes such as chorioamnionitis will lead to preterm birth. Key words: Fetal membranes; Pregnancy; Premature birth