SUMMARY Objective: The objective of this study is to determine if the maternal prepregnancy overweight and obesity are related to risk of cesarean delivery and other obstetrical complications. Methods: Transversal study of 1223 nulliparous women that delivered in our maternity between August 2007 and April 2008. Women were categorized by the body mass index (BMI): 482 normal weight (BMI: 18.5-24.9 Kg/m 2 ), 419 overweight (BMI: 25-29.9 Kg/m 2 ) and 322 obesity (BMI: ≥30 Kg/m 2 ). Obstetrical complications, labor and its complications, and neonatal weight were studied. Results: Women who were overweight was nearly twice as likely to deliver by cesarean section as women with normal weight (OR: 1.8; 95%CI 1.4-2.9). Obese women experienced a three-fold increase in risk of cesarean section in comparison to normal weight women (OR: 3.02; 95%CI 2.6-4.5). Number of labor inductions was higher in overweight and obese group (OR: 1.6; 95%CI 1.3-1.9) and (OR: 2.1; 95%CI 1.7-2.9) respectively in comparison to control group. The highest risk of fetal macrosomia (weight >4000 g) was in the overweight (OR: 1.5; 95%CI 1.4-2.2) and obese women (OR: 1.9;