Abstract : To determine the risk factor of gestational diabetes mellitus among pregnant women and compare them with the control group. The sample was gathered using (non-probability-convenient-sampling) and the sample size was 200 in Karbala city (Al-Hyndia hospital and The typical health center in Al-hyndia) (with 100 GDM patients and 100 non-GDM controls). The study started on 1 September 2019 to 1 April 2020. The data was gathered through a direct interview with a special questionnaire that included (age, education, occupation, parity, gravidity, diabetes mellitus history, etc.). According to the findings, the majority of cases of were (24.5 percent) for the age group (20-29) years. It was discovered that various essential characteristics, such as age, education level, and family history of diabetes mellitus, are connected with gestational diabetes mellitus. However, one factor that is not associated with gestational diabetes mellitus is smoking habit. The factors showed significant association with GDM are age, previous history of gestational diabetes, family history of diabetes mellitus, gravidity, parity, previous history of abortion, previous history of stillbirth, previous history of macrosomia, polycystic ovarian, type of previous delivery and previous history of hypertension. And factor not have significant associated with GDM is previous history of hypertension and smoking habit. All pregnant women should visit the hospital/clinic health post for antenatal check - ups and Screening for GDM must be performed compulsory to all pregnant mothers.