Background and purpose: One step 75gr glucose tolerance test is introduced as a replacement for classic two step GTT for diagnosis of gestational diabetes (GDM). This study was designed to evaluate the prevalence of gestational diabetes based on new criteria and its related fetomaternal adverse effects.

Materials and methods: An analytic-descriptive study was performed in 271 pregnant women attending Tehran Javaheri Hospital in 2015. They underwent a 75-g glucose tolerance test. The frequency of GDM was calculated with CI95% and data was analyzed in SPSS 21 applying student t test for quantitative variables and Chi square for qualitative variables.

Results: The mean age of the participants was 30.5±4.6 years. The frequency of GDM was 24% of whom 15.4% required medication. Significant correlation was found between age, BMI, positive family history of diabetes mellitus and history of GDM in previous pregnancies and GDM (P<0.05). In this study the frequency of gestational hypertension was significantly higher in mothers with GDM compared with the normal group (P=0.003). There was no any significant difference between the two groups in other fetomaternal complications.

Conclusion: GDM was found to be highly prevalent but only few cases required medication. Also, no significant difference was seen in fetal complications between the two groups, therefore, larger studies are suggested to consider the benefits and cost effectiveness of new criteria.