BACKGROUND: Recent studies have implicated a variety of infections, including periodontal diseases, as risk factors for adverse pregnancy outcomes such as prematurity and low birth weight. RATIONALE: A number of studies have shown that bacterial vaginosis is related to preterm and/or low birth weight (PT/LBW), which continues to be a significant cause of infant morbidity and mortality. It is also possible that other infectious processes, including periodontal diseases, contribute to PT/LBW. This systematic review examines the literature to determine the possible relationship between PT/LBW and periodontal diseases. FOCUSED QUESTION: Does prevention/control of periodontal disease as compared to controls have an impact on the initiation/progression of adverse pregnancy outcomes? SEARCH PROTOCOL: MEDLINE, pre-MEDLINE, MEDLINE Daily Update, and the Cochrane Oral Controlled Trials Register were searched to identify published studies that related variables associated with PT/LBW and periodontal disease. Searches were performed for articles published through October 2002. INCLUSION CRITERIA: Randomized controlled clinical trials (RCTs), case-control, and cohort studies were included. Study populations included mothers, with or without periodontal disease, who gave birth to preterm and/or mature infants. The interventions considered included all forms of periodontal therapy. EXCLUSION CRITERIA: Only studies on humans were included. DATA COLLECTION AND ANALYSIS: Due to study heterogeneity, meta-analysis was not possible. MAIN RESULTS: 1. Of the over 660 studies identified, 12 (6 case-control, 3 cross-sectional and longitudinal, and 3 intervention) met inclusion and exclusion criteria and were included in the analysis. 2. While several studies implicated periodontal disease as a risk factor for PT/LBW, few assessed the impact of the prevention and treatment of periodontal disease on outcomes. 3. Several epidemiologic studies did not support periodontal disease as a risk factor for PT/LBW. REVIEWERS' CONCLUSIONS: 1. Periodontal disease may be a risk factor for PT/LBW. 2. Additional longitudinal, epidemiologic, and interventional studies are needed to validate this association and to determine whether it is causal. 3. It is not yet clear whether periodontal diseases play a causal role in adverse pregnancy outcomes. 4. Preliminary evidence to date suggests that periodontal intervention may reduce adverse pregnancy outcomes.