Specific mediators such as TNF-α, IL-1β, IL-6, IL-7, IL-8, PGE2, MMP-8, MMP-9, CRP, CXCL8, MCP-1, CCL2, COX-2, sVCAM-1 and sICAM-1 play a part in linking periodontitis to preterm delivery by promoting oxidative stress, stimulating uterine contractions and recruiting macrophages to the inflamed placenta, which worsens its premature rupture. Here, MMP9 is linked to periodontitis.