Differential activity of the gelatinases (matrix metalloproteinases 2 and 9) in the fetal membranes and decidua, associated with labour

Degradation of the extracellular matrix in fetal membranes has been implicated in the rupture of fetal membranes, the process of parturition and placental detachment from the decidua after parturition. In this study we assessed labour‐associated changes in gelatinase activity in cultured human amnion, chorion and decidua, as well as in amniotic fluid. We found that in media conditioned by decidua, following the establishment of uterine contractions, matrix metalloproteinase‐2 (MMP‐2) activity is increased while the protein tissue inhibitors of matrix metalloproteinase‐1 (TIMP‐1) level is decreased. The formation of a 130 kDa gelatinase band was also significantly increased after contractions began. In media conditioned by chorion, the initiation of uterine contractions did not change MMP activity or TIMP‐1 levels. However, an increase in MMP‐9 activity and a decrease in TIMP‐1 protein levels were observed following the establishment of uterine contractions in media conditioned by amnion. We suggest that this differential spatial regulation provides a form for modulatory hierarchal activity of the MMPs in the onset of labour allowing rupture of the membranes while avoiding premature placental separation.