BACKGROUND:The presence of lower genital tract infections poses a threat to the health of a woman. During pregnancy, these infections may also have a direct effect on the fetus or may indirectly predispose to fetal damage secondary to premature labour or premature rupture of membranes. Early detection is thus important because maternal physiological alterations and the presence of a fetus may hamper the diagnosis and the management of such infections. Antepartum treatment of lower genital tract infections or bacterial colonization has been found to reduce the incidence of preterm births. OBJECTIVES: To study the impact of education and socio-economic background, to assess diagnostic efficacy in pregnancy, to study the effect of intervention on the outcome of pregnancy and finally, to study the appropriate trimester for taking a cervicovaginal swab in pregnant women. MATERIALS AND METHODSOur case study was a prospective study involving 100 pregnant women following up in the outpatient department of a community hospital from 2008-2010 with respect to their cervicovaginal microbial growth in each trimester. Patients were divided into culture positive and negative groups and treated accordingly RESULTS -In our study, we found that streptococcus, candida and staphylococcus were the most commonly prevalent among all the microorganisms isolated. Out of 100 women, 27 were swab positive in the 1 st trimester with an increasing trend of 1% in swab positivity in subsequent trimesters. Among swab positive cases, 51.85%(1 st ), 50%(2 nd ) and 51.72%(3 rd ) landed up in preterm labour with or without PROM. CONCLUSION -There was a very high positive correlation between the incidence of a positive swab culture and preterm events. We found that the best time for a cervicovaginal swab was during the 3 rd trimester. Our study had a high negative predictive value i.e. absence of growth were best in predicting that cases would not go in to preterm labour INTRODUCTION: Preterm labour is defined as the presence of uterine contractions of sufficient frequency and intensity to effect progressive effacement and dilation of the cervix prior to term gestation (between 20-37 weeks). Preterm births occur in approximately 12% of pregnancies and is the leading cause of neonatal mortality today (1,2) . The exact mechanism of preterm labour is yet unknown but is postulated to be commonly due to decidual haemorrhage (abruption, mechanical factors such as uterine over distension as in multiple gestation or polyhydramnios), cervical incompetence (trauma/cone biopsy), cervical inflammation (due to vaginosis/ trichomonas), uterine distortion (Mullerian anomalies, fibroid), maternal inflammation or fever, hormonal changes or utero-placental insufficiency (hypertension, diabetes, drug abuse etc.) (1,2) .