Tehran University of Medical Sciences Journal of Biostatistics and Epidemiology 2383-4196 4 4 2019 03 13 216 221 Mahmoud Parham Clinical Research Development Center, Qom University of Medical Sciences, Qom, Iran Mohammad Bagherzadeh Clinical Research Development Center, Qom University of Medical Sciences, Qom, Iran Mohammad Hossein Ghasembeglou Qom University of Medical Sciences, Qom, Iran Jamshid Vafaeimanesh Gastroenterology and Hepatology Disease Research Center, Qom University of Medical Sciences, Qom, Iran 2018 10 13 Background & Aim: Gestational diabetes mellitus (GDM) is the most common metabolic disorder in pregnancy which is caused due to insulin resistance and carries several risks for the mother and neonate. So, an updated data from its prevalence in different geographical areas is important. Methods & Materials: This cross-sectional analytic study was performed on pregnant women referring health centers in Qom city from June 2013 to September 2014 for prenatal care. In week 10 of pregnancy, fasting blood sugar (FBS) was checked for all participants and those who had FBS >126mg/dL for 2 times were excluded from the study and all participants who remained in the study underwent oral glucose tolerance test with 75 gr glucose at 24-28weeks of gestation. Gestational diabetes was diagnosed on the basis of at least one abnormal responses of glucose≥92mg/dL, 1-hour glucose ≥180 mg/dL or 2-hour glucose ≥153mg/dL. Results: A total of 4988 pregnant women enrolled the study. Based on 75g oral glucose tolerance (OGT) test results at 24-28 weeks of gestation, 1036 women (20.76%) had gestational diabetes. Gestational diabetes was significantly associated with maternal age, body mass index, history of gestational diabetes, a family history of type II diabetes in first-degree relatives, history of preterm labor, known hypothyroidism before pregnancy and history of macrosomia. Conclusion: Gestational diabetes has a high prevalence in Qom city, and it seems that new studies are needed to determine its prevalence in other regions. https://jbe.tums.ac.ir/index.php/jbe/article/view/218 https://jbe.tums.ac.ir/index.php/jbe/article/download/218/178