Background: Diabetes with pregnancy is a known clinical risk factor associated with fetal macrosomia. The rationale for performing an elective cesarean section includes a potential reduction in perinatal complications, especially those related to macrosomia. Objective: This study aimed to assess the accuracy of HbA1c and umbilical cord thickness in prediction of fetal macrosomia in diabetic pregnant women. Patients and Methods: The study included 100 diabetic pregnant, 27 - 28 weeks gestation, gathered from Inpatients and Obstetric Outpatient Clinic of Bab Alshariya University Hospital attending for routine antenatal care. Results: At a criterion of > 211 mm2 , the umbilical cord area measured at 27 – 28 weeks of gestation was able to predict high birth weight (macrosomia), with a sensitivity of 90.5% and a specificity of 91.7%. The area under the curve for the ROC was 0.9294, with a 95% confidence interval of 0.8608 to 0.9702, which was found to be statistically highly significant (p = 0.0001). When compared the ROC curves of both the umbilical cord area and the glycated hemoglobin, it was found that umbilical cord area is more reliable in predicting fetal macrosomia at the right criterion, the difference between the predictive efficiency for both parameters was found to be statistically highly significant. Conclusion: Macrosomia is a cause of the worst of obstetric emergencies such as shoulder dystocia, birth asphyxia and postpartum haemorrhage. Shoulder dystocia cannot always be predicted accurately. However, predicting macrosomia can help to identify the population at risk of such complications.