Objectives: To determine the impact of obesity on decision-making concerning mode of delivery and to compare these data versus the reliance on the Ten-group Robson Classification System (RCS) alone. Patients & Methods: 554 parturient free of pregnancy-associated medical diseases were evaluated clinically at time of enrolment for RCS class and at time of admission for delivery, for body mass index (BMI) grading. Mode of delivery was predetermined according to RCS class and clinical judgment taking in consideration maternal age and BMI. Parturient distribution after labor according to mode of delivery was compared to that predetermined by clinical and RCS evaluation. Results: According to RCS class, elective CS was predicted for 204, spontaneous deliveries for 166 and 184 parturient were predicted to require induction of labor. Clinically, 163 parturient were predicted to have unaided vaginal delivery, 95 parturient will have CS and 296 parturient will require induction of labor. The probability to have CS was significantly higher on reliance on RCS grading system. Actually, 327 women had unaided and 23 had instrumental vaginal delivery and 204 required CS. The actual frequency of CS was related to nulliparity, history of previous CS, BMI and RCS grading. Statistical analyses defined nulliparity as the significant sensitive and high BMI as the significant specific predictor for CS. In comparison to parturient had ≤32 kg/m2, the cumulative hazard to have CS was increased by 10% with BMI >32-34 kg/m2, 45% with BMI 34-35 kg/m2 and by 100% at BMI≥ 36.5 kg/m2. Conclusion: The Robson Classification System had good true negative, but high false positive predictive values for CS. Adjustment according to BMI within Robson groups significantly reduced the need for CS and may improve the decision for augmentation, instrumental and operative delivery.