Background and objectives: There is still debate regarding potential relationships between maternal periodontitis during pregnancy and adverse pregnancy outcomes. The aim of this systematic review was to synthesize the available epidemiological evidence on this association.
Data sources: Combined electronic and hand search of MEDLINE, EMBASE, WEB OF SCIENCE and Cochrane Central Register databases.
Study eligibility criteria: Original publications reporting data from cross-sectional, case-control or prospective cohort epidemiological studies on the association between periodontal status and preterm birth, low birthweight (LBW) or preeclampsia. The search was not limited to publications in English. All selected studies provided data based on professional assessments of periodontal status, and outcome variables, including preterm birth (<37 weeks gestation), LBW (<2500 g), gestational age, small for gestational age, birthweight, pregnancy loss or miscarriage, or pre-eclampsia.
Participants: Pregnant women with or without periodontal disease, and with or without adverse pregnancy outcomes, assessed either during pregnancy or postpartum. No intervention studies were included. Study appraisal and synthesis methods - Publications were assessed based on predefined screening criteria including type of periodontal assessment, consistency in the timing of the periodontal assessment with respect to gestational age, examiner masking and consideration of additional exposures and confounders.
Results: Maternal periodontitis is modestly but significantly associated with LBW and preterm birth, but the use of a categorical or a continuous exposure definition of periodontitis appears to impact the findings: Although significant associations emerge from case-control and cross-sectional studies using periodontitis "case definitions," these were substantially attenuated in studies assessing periodontitis as a continuous variable. Data from prospective studies followed a similar pattern, but associations were generally weaker. Maternal periodontitis was significantly associated with pre-eclampsia.
Limitations: There is a high degree of variability in study populations, recruitment and assessment, as well as differences in how data are recorded and handled. As a result, studies included in meta-analyses show a high degree of heterogeneity.
Conclusions and implications of key findings: Maternal periodontitis is modestly but independently associated with adverse pregnancy outcomes, but the findings are impacted by periodontitis case definitions. It is suggested that future studies employ both continuous and categorical assessments of periodontal status. Further use of the composite outcome preterm LBW is not encouraged.