Evidence grade associating periodontitis to preterm birth and/or low birth weight: I. A systematic review of prospective cohort studies

Aim: The aims of this systematic review (SR) were to evaluate the association between maternal periodontitis and preterm birth (PB) and/or low birth weight (LBW), and the methodological quality of prospective cohort studies conducted for such a purpose. Methods: MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched up to and including October 2010 to identify prospective studies on the association of periodontitis with PB and/or LBW. Search was conducted by two independent reviewers. The methodological quality of the observational studies was assessed using a specially designed methodological tool. Random effects meta-analyses were conducted thoroughly. Results: Search strategy identified 1680 potentially eligible articles, of which 12 prospective studies were included. One cohort study had their data reported in two articles. Of the 11 studies, 10 showed a high methodological quality and one a medium methodological quality. Nine studies (81.8%) found an association between periodontitis and PB and/or LBW. Meta-analysis showed a significant risk of preterm delivery for pregnant women with periodontitis [risk ratio (RR): 1.70 (95% confidence interval (CI): 1.03, 2.81)] and a significant risk for LBW [RR: 2.11 (95% CI: 1.05, 4.23)] or PB/LBW [RR: 3.57 (95% CI: 1.87, 6.84)], as well as a high and unexplained degree of heterogeneity between studies. Conclusion: Although this SR found a consistent association between periodontitis and PB and/or LBW, this finding should be treated with great caution until the sources of heterogeneity can be explained.