PTGS2 and periodontitis: 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.