Periodontal disease and preterm birth: Findings from the 2015 Pelotas birth cohort study.

OBJECTIVES: To verify the association between periodontal conditions and preterm birth. MATERIALS AND METHODS: This study used data from the 2015 Pelotas Birth Cohort Study, Brazil. Pregnant women expected to give birth in 2015 were interviewed and dentally examined by a trained dentist, with periodontal measures collected in all teeth, six sites per tooth. Exposure was periodontal disease. Outcomes were preterm birth (all births <37 weeks of gestational age) and early preterm birth (<34 weeks). Analysis was carried out using Poisson regression according to a directed acyclic graph. RESULTS: A total of 2,474 women participated in the study. Incidence of preterm births was 10.2% and of early preterm births was 3.5%. Frequency of gingivitis was 21.7%, and periodontitis was 14.9%. Periodontitis was associated with a risk almost two times higher of having early preterm delivery compared with healthy pregnant women (RR 1.93; 95% CI 1.09-3.43). Presence of 5+ mm periodontal pocket with bleeding on probing was also associated with higher risk for early preterm delivery. CONCLUSIONS: The association between periodontal disease in pregnancy and the occurrence of preterm delivery is sensitive to the case definitions. Periodontal disease increased the risk of early preterm delivery.