Context: original. Aims and Objectives: To study the relationship between bacterial vaginosis in third trimester and preterm labor. To study the relationship between periodontal infection in third trimester and preterm labor. To find out the incidence of bacterial vaginosis and periodontal infection in antenatal patients at PGIMSR, New Delhi. Settings and Design: The prospective case control study. Methods and Material: A total of 500 patients were enrolled for the study. The incidence of Bacterial vaginosis and periodontal infection was calculated for the hospital. Out of these 500 patients, 200 patients were randomly selected and divided into 4 groups. Group 1(n = 50): Patients with no evidence of bacterial vaginosis and periodontal infection. Group 2(n = 50): Patients positive for periodontal infection. Group 3 (n = 50): Patients positive for bacterial vaginosis Group 4(n = 50): Patients positive for periodontal infection and bacterial vaginosis. Group 1 was the control group with sample size of 50 patients. Groups 2, 3, 4 were compared with the control group and correlated to the preterm birth and perinatal outcomes. Results: 14(29.2%) patients in group 1 had PROM, 29(59.2%) patients in group 2 had PROM, 15(31.3%) patients in group 3 had PROM and 19(40.4%) patients in group 4 had PROM. The difference in all the groups was statistically significant (p<0.05) (Table 6, Figure 6). Conclusion: Significant correlation is seen between periodontal infection and preterm labor & preterm premature rupture of membranes. Bacterial vaginosis is not found to be associated with preterm labor. Both of them have no significant correlation with perinatal outcomes. 

Keywords: Bacterial Vaginosis; Periodontal Infection and Preterm Labour.