Purpose:  The study aim was to assess the relation between maternal blood levels of insulin like growth factor 1& its relation to neonatal macrosomia. Methods: 68 pregnant women was included in the study, divided into two groups as 34 women was diabetic (            TIDM, TIIDM or GDM) the other 34 was healthy women as control group. We obtain a venous blood sample ante-natally from each mother after consent, IGFI estimated on each sample. Results: Between the two mother groups the significant difference was noted regarding the laboratory testing for both random blood sugar and for insulin like growth factor1.  Mean random blood sugar in diabetic group was 241 mg/dl   ranging from 130 to 400 mg/dl.  While; mean random blood sugar in control group was 109 mg/dl ranging from 78 to 200 mg/dl. With student T test 11.9 and P < 0.001** . Mean value of serum level of IGF1 in diabetic group founded to be 11.3ng/ml with a range of  8.8 to 13 ng/ml. In control group mean value of IGF1 8.1 ng/ml ranging from 4.2 to 12.6 ng/ml. with the student T test 7.1 and P value <0.001** Conclusions: insulin like growth factor 1 was significantly higher in diabetic mothers blood which all give birth to macrosomic babies, IGF1 can be used as a predictive factor of fetal macrosomia