Introduction: Pregnancy outcomes and infant health is an important issue. Considering the existingcontradictions about the impact of maternal body mass index (BMI) on these outcomes, the present studywas conducted to examine the relationship of BMI with neonatal outcomes in Gilan’s pregnant women.Materials and Methods: This retrospective study was conducted based on existing data on 511 pregnantwomen in Gilan province. Data collection was based on their health record information in health centers.Neonatal Outcome was studied on based BMI pre- pregnancy.Results: In this study, the average of maternal primary BMI and newborn weight were 25.69±4.88 kg⁄m2,3272.09±388.86 gram, respectively. Also the born babies were mostly male gender. Statistical testsbetween mother’s primary BMI and infant weight showed a statistically significant relationship, and also,there were not showed a significant difference relationship between mother’s primary BMI and thevariables of height and head circumference of new born, jaundice, respiratory distress, and sex of infant.Conclusion: According to the results and the effect of BMI on some of neonatal outcomes, it isnecessary that educational, advocacy and counseling programs for mothers to be done to ensuremother’s good physical condition before pregnancy. Thus, it is caused the promotion of themothers’ health and infants are provided.