Background:Obesity was related with high risks for maternal morbidity and mortality, Pregravid obesity is distinct potentially modifiable risk factors with differing associated adverse complications. Objectives: This study aimed to evaluate the effect of BMI on labor duration and determine the obesity effect on delivery mode in primigravida at term whether C/S rates are increased in overweight and obese women. Patients & Methods: This case control study was done in Gynecology department, Faculty of Medicine, Zagazig University Hospitals during the period from January to June 2019. It included 100 women (50 laboring primpgravidae Overweight and obese pregnant women, with (BMI≥25 kg/m2) at ≥ 37 weeks in the Obstetrics and 50 Healthy, primigravidae women (BMI 18.5- 24.9 kg/m2) with a singleton vertex cephalic pregnancy of a gestational age 37-42 weeks as a control group). Results: The results of the study revealed that the duration of 1st stage of labor are differing significantly among obese, overweight, and normal-weight primigravidae. There is directly proportional association between maternal BMI and the length of the 2nd stage in primigravidae. The C/S rate was significantly different between obese and normal-weight women, it was (54%) in overweight and obese group and (18%) in normal-weight group, there was no statistical significant difference between the both groups regarding postpartum complications.. Conclusion:Labor progress in obese is more slowly with significantly longer labor duration especially first and second stages in comparison to average weight concerning BMI. Obese primigravida has more chance for induction failure and risk for C/S and its complication.