A previous study by Wang et al. [15] has shown that matrix metalloproteinase 1 (MMP1), whose genetic variation is associated with susceptibility to PPROM [16], is regulated at the epigenetic level, specifically by DNA methylation, and that MMP1 promoter methylation status correlates with its expression in the amnion and association with PPROM. Here, MMP1 is linked to preterm premature rupture of the membranes.