Scientific literatures demonstrate the hypotheses that periodontal disease, as a source of subclinical and persistent infection, may induce systemic inflammatory and immunological responses that increase the risk of adverse pregnancy outcomes. This study aim to examine the existing evidence on the relationship between periodontal disease and adverse pregnancy outcomes. Periodontal disease with increase of inflammation and through immunological paths may be associated with an increased risk of adverse pregnancy outcome. However, further integrated and well-designed studies seem to be needed for confirmation.