The objective of this study was evaluation of excessive pregnancy weight gain effect in non-diabetic women with normal pre-pregnancy BMI on macrosomia of neonate. In a descriptive cross-sectional study, neonate weighs of all term pregnancy in non-diabetic women with normal pre-pregnancy BMI delivered from 2002 to 2004 in Shaheed Sadoughi Hospital in Yazd, were evaluated. Compared with mothers with normal pregnancy weight gain, the risk of macrosomia in offsprings was significantly elevated in women who had excess weight gain. The odds ratio (OR) was 3.3 (95% confidence interval [CI] = 2.2 - 5.1, P = 0.0001). Given the complications associated with delivering large babies, women may benefit from not gaining excess weight in pregnancy.