Evidence suggesting that MMP1 plays a key role in PPROM include: elevated levels of MMP1 have been detected in the amniotic fluid of PPROM patients in both the presence and absence of infection (Maymon et al., 2000), a single nucleotide polymorphism in the promoter region of the MMP1 gene is associated with an increased risk of PPROM and changes in DNA methylation in the promotor region of the MMP1 gene have been associated with an increased risk of PPROM (Wang et al., 2008). This evidence concerns the gene MMP1 and infection.