Objective: Periodontitis may be a risk factor for preterm labor due to the presence of pro-inflammatory bacteria and cytokines in the bloodstream during infection, which can affect the farther organs. The aim of this study was to investigate the relationship between oral infections and preterm labor pain. Methods: This case-control study was performed on 100 pregnant women referred to the women and maternity ward of Ahvaz Imam Khomeini Hospital. Patients divided into two groups of pre-term and term patients. Demographic characteristics and midwifery data such as preterm labor risk factors were recorded by approved questioner in both groups. At follow-up and within 48 hours postpartum, patients were examined by a knowledgeable dentist for oral infections. Modified Machtei's index was used to determine the presence of periodontitis in patients and finally data were analyzed using SPSS version 22 software and Significance level was considered less than 0.05 (p<0.05). Results: The mean age of the patients was 28.91±4.59 years (28.94 ± 4.87 vs 28.88±4.34 in case and control group respectively (p = 0.94).) None of the patients in the two groups had any history of smoking and no previous preterm pregnancy and bleeding was reported in any of the patients. Evaluation of patients in both groups showed that 39 cases had oral infections in the case group and 31 cases had oral infections in the control group, which was not statistically significant (p = 0.08). Conclusion: Our findings indicate that prevalence of periodontal diseases in preterm mothers was not statistically significant more than control group. Further studies are needed to determine exact relationship between oral infections and preterm labor.