Background: Fetal growth in a diabetic pregnancy is a complex process and maternal metabolic parameters other than glucose levels should be addressed to reduce the risk of macrosomia in this group of patients.Objective: To determine the association between maternal serum lipid levels, particularly triglycerides (TG) levels and newborn birth weight (BW)Patients and methods: A total of 41 pregnant women at gestational age of 26-28 week with controlled diabetes as denoted by serum HbA1C level< 7 mg% were included. Fasting serum level of TG, total cholesterol (TC), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) were measured and correlated to fetal weight by ultrasonography and newborn BW.Results: Maternal fasting serum TG levels were significantly higher in mothers of macrosomic newborns compared to other mothers; (256 ± 50 mg/dl vs208 ± 46 mg/dl , p=0.009) however, no significant correlations were found between newborn BW and maternal TC or LDL. After adjusting for confounding variables including maternal age, prepregnancy body mass index, previous history of macrosomia and serum HDL level, maternal hypertriglyceridemia at 26-28 weeks’ gestation remained an independent parameter for identifying macrosomic newborn with a sensitivity of 73% and a specificity of 65%. Conclusions: Fasting serum TG levels at mid-term diabetic pregnancy correlates positively with neonatal BW, and may be considered as an independent predictor of fetal overgrowth at term.