Background: Earlier studies on the association between oral inflammation and preterm birth limited the inflammation source to periodontal disease. This might have caused an underestimation of the total inflammatory burden from the oral cavity.
Methods: We conducted a postpartum cross-sectional study of 328 Finnish women with singleton births, of whom 77 had preterm births and 251 had full-term births. Gingival bleeding on probing, probing depth, and the presence of dental calculus and mouth ulcers were recorded; the oral inflammatory burden index (OIBI) was constructed based on these clinical findings. A data-driven oral inflammation score (OIS) was also created by stochastically combining the same parameters assessed independently. We used the t, Mann-Whitney, and chi(2) tests for univariate analyses and multivariate logistic regression methods to examine the association between OIBI/OIS and preterm birth. The confounders adjusted for were age, smoking (past, present, and never), diabetes (type 1, type 2, and gestational), primiparity, antimicrobial treatment as a proxy for systemic infection, infertility treatment, and weight gain during pregnancy.
Results: OIBI was significantly associated with preterm birth after adjusting for confounding factors (odds ratio [OR], 1.85; 95% confidence interval [CI]: 1.10 to 3.10; P = 0.02). Without adjusting for weight gain, OIS was significantly associated with preterm birth (OR, 1.97; 95% CI: 1.09 to 3.57; P = 0.03); however, this association became non-significant after adding weight gain to the model.
Conclusion: The combined effects of multiple oral infections were significantly associated with preterm birth.