Amniotic fluid concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 during pregnancy and labor

OBJECTIVE: This study was undertaken to determine whether obstetric factors affect the concentrations of matrix metalloproteinase 9 and tissue inhibit or of metalloproteinase 1 in the amniotic fluid. STUDY DESIGN: We prospectively collected amniotic fluid samples from 109 wo men at various stages of pregnancy and labor and determined matrix metallop roteinase 9 and tissue inhibitor of metalloproteinase 1 concentrations by m eans of enzyme-linked immunosorbent sandwich assay systems. With multiple r egression analysis we evaluated relationships between amniotic fluid matrix metalloproteinase 9 concentration and tissue inhibitor of metalloproteinas e 1 concentration and the following factors. gestational age, presence of l abor, cervical dilatation, membrane status, presence of clinical chorioamni onitis, and microbial colonization of the amniotic fluid. RESULTS: The detectable presence of amniotic fluid matrix metalloproteinase 9 was independently associated with intra-amniotic infection, labor, cervi cal dilatation, and spontaneous rupture of membranes. Chorioamnionitis and amniotic fluid matrix metalloproteinase 9 concentrations were correlated wi th tissue inhibitor of metalloproteinase 1 levels. CONCLUSIONS: Intra-amniotic infection, advanced labor, and rupture of membr anes before the onset of labor were independently associated with the prese nce of matrix metalloproteinase 9 in the amniotic fluid. Both pathologic an d physiologic processes appear to produce shifts in the balance between deg radation and synthesis of the extracellular matrix.