Background: The increasing prevalence of obesity worldwide has prompted the World Health Organization (WHO) to designate obesity as one of the most important global health threats. The epidemic is especially pronounced in women of reproductive age. Prepregnancy obesity is an independent risk factor for maternal and neonatal morbidity and mortality. The origin of this epidemic is unhealthy lifestyle – high energy and high-fat diet and physical inactivity. During periconceptual period and pregnancy, the composition of a woman’s diet is of particular importance, as it may influence the pregnancy, the delivery and the health of the mother and the infant later on, so an excessive gestational weight gain (GWG) is not recommended. The aim of our study is to clarify the complications related to excess prepregnancy body weight on maternal and fetal health. Methods: Hundred obese pregnant women with BMI (30-40 Kg/m2) measured at first trimester were prospectively enrolled into this study. Routine blood pressures, random blood sugar measuring and ultrasonographic follow up are required during pregnancy for early detection of any complications related to maternal obesity and excessive gestational weight gain (GWG). Results: cases statistically evaluated in these study were 100 pregnant females with mean age 27.34 years + 5 years SD and mean BMI 32.97 Kg/m2 + 2.92 Kg/m2 SD. Denoting in our study, the effect of maternal obesity om maternal and fetal health. Conclusion: A causal relationship between the prepregnancy BMI and obstetric complications is proven. Weight management is important for every women of reproductive age. Thus, medical Practice must consider these complications by providing early detection and management to improve both maternal and neonatal outcome.