Although the exact mechanisms that clearly explain the participation of periodontitis in the adverse effects of pregnancy have not yet been established, some theories try to seek an explanation through two mechanisms: by the action of periodontal pathogens or by the effect of inflammatory mediators, such as interleukin-1 (IL-1), IL-6, IL-8, tumor necrosis factor-α (TNF-α) or prostaglandin E2 (PGE2), in the fetal-placental unit (6). The gene discussed is TNF; the disease is periodontitis.