Objective: To study the prevalence of Gestational diabetes mellitus and to assess the impact of early universal screening to detect Gestational diabetes mellitus. Materials and Methods: Consecutive 1106 pregnant women were screened for Gestational diabetes mellitus at their first prenatal visit during the study period of February 2012 to January 2013. All the women were screened with a initial 50 gram one hour glucose challenge test (GCT) and those women who tested positive were subjected to a standardized 75 gram oral glucose tolerance test(OGTT). The prevalence of Gestational diabetes mellitus and its association with age, infertility, obesity, hypertension, family history of diabetes was studied. The impact of early universal screening for GDM was assessed. American diabetic association (ADA) and International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria for diagnosis of Gestational diabetes mellitus was used in our study. Results: Of the total 1106 pregnant women who were screened with the initial 50 gram one hour glucose challenge test (GCT), 458 (41.4%) had their one hour plasma glucose value >130gm/dl. Of the 440 women who responded to and underwent the subsequent 75gram OGTT, 158 (61.2%) had one abnormal value, 73(28.2%) had two abnormal values and 27 (10.5%) had three abnormal values. 64(24.8%) of them had fasting plasma glucose >= 92/dl. 36(13.9%) women were found to have GDM in the first trimester (12 weeks), 43 (16.7%) in the 13-18 weeks, 114 (44.1%) in the 19-28 weeks and 65 (25.2%) in the third trimester(28 weeks). The overall prevalence of GDM was 23.3%. There was increased association of GDM with increasing age, parity, family predisposition and infertility. Conclusion: It is evident that there is increased prevalence of GDM in Indian population. Universal screening for GDM is better to routine risk factor based screening and it should be done at the first prenatal visit for early diagnosis of glucose intolerance in pregnancy especially in countries like India. There is increased association of GDM with infertility, advanced age, obesity, family predisposition and parity.