Objective: To identify the effect of high maternal body mass index before pregnancy on the outcome of pregnancy.   Methods: A retrospective study was conducted. Between January 1990 and January 2000, 488 obese pregnant women with body mass index (BMI) >30Kg/m2 who received prenatal care and delivered at Prince Rashid Military Hospital were identified from hospital files and records. A control group made of 520 pregnant women with BMI <30Kg/m2, were matched for maternal age and parity. All variables of antepartum, delivery, and postpartum complications as well as neonatal outcome were compared between the two groups and the data was analyzed.   Results: Compared with a control group, we found a statistically significant increased risk in the obese patients through pregnancy, delivery, and post-partum. During the antepartum period, obese pregnant were more likely to develop pregnancy-induced hypertension, gestational diabetes, intrauterine fetal death, and intrauterine growth retardation. In the Intrapartum period, they also were significantly more likely to be delivered by cesarean section, had a macrocosmic baby, shoulder dystocia, meconium aspiration, and induced labor. During the postpartum period, perineal tears, postpartum hemorrhage, blood transfusion, infections, thromboembolizm, and psychiatric illnesses, were significantly increased among obese compared with lean women.      Conclusion: High maternal Body Mass Index before pregnancy can contribute to both fetal and maternal complications of pregnancy. Thus pregnancy in obese women should be considered as a high risk factor; in order to prevent such serous complications by special care. Further prospective studies are needed to asses the out come of pregnancy with obesity.