MMP2 and preterm premature rupture of the membranes: Mean concentrations of matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9), TIMP metallopeptidase inhibitor 1 (TIMP-1), TIMP metallopeptidase inhibitor 2 (TIMP-2), and collagen VI (COL-6) were not significantly different in cases with PPROM compared with those in controls (p = 0.91, p = 0.73, p = 0.25, p = 0.42, and p = 0.85 respectively).