A pilot study of the association between cariogenic oral bacteria and preterm birth*

Objectives: We examined the associations between preterm birth and low birth weight and maternal caries history, maternal periodontal status, and salivary levels of mutans streptococci and Lactobacilli. Design: This study was a matched case-control study in women during their pregnancy or up to 8 weeks after delivery. Subjects and methods: Thirty-four women delivering before 37 weeks gestation were recruited along with 73 term controls matched for age and race/ethnicity. Demographic and obstetric information was collected from questionnaires and medical records and oral examinations along with commercial salivary tests were completed within the study groups. Main outcome measures: The main outcome variables were the preterm birth and low birth weight status. The independent variables measured were the salivary levels of Lactobacilli and mutans streptococci and the caries and periodontal status of the subjects. Results: The odds ratio comparing low levels of bacteria in preterm mothers and controls was statistically significant for Lactobacilli (odds ratio (OR) = 3.45, 95% confidence interval (CI) = 1.27 to 10.00) and almost significant for mutans streptococci (OR = 2.63, 95% CI = 0.95 to 8.33). Clinical caries and periodontal disease measures did not differ significantly between groups. Conclusion: Within the limitation of our study, low levels of Lactobacilli in saliva were found to be associated with preterm birth.