Obesity is a global problem not only among women but also among men. During last 40 years the number of obese women increased at least 3 times. In Europe the frequency of obesity during pregnancy range from 5 to 20%. Obesity among women is an important medical problem because it is associated with different gynecological and obstetrical complications. From the etiological point of view genes play a role in predisposing individuals to this complication, but it seems that environmental exposition to risk factors is necessary for the expression of the obese phenotype. Polygenic nature of this complication makes it impossible to select the group of women with high risk of this complication. Meta analysis of observational studies indicated strong association between obesity nad fetal macrosomia, pre-eclampsia, condition of the newborn (low Apgar score), rate of emergency cesarean section and depression. The risk of miscarriage in the group pregnant women after IVF, stillbirth, postpartum hemorrhage and preterm birth is significantly higher in obese women. The main role of such complications are metabolic changes in obese women. It is also proven that obesity is an important risk factor for the offspring related to its unfavourable metabolic programming. Obesity of the mother places offspring at high risk o developing chronic diseases such as obesity, metabolic syndrome, non-alcoholic fatty liver disease, type 2 diabetes and possibly even autism, Prevention of the obesity during pregnancy but also in other periods of women life is an important task for the medicine. Adequate prophylaxis, education, diet, physical activity, control of weight gain during pregnancy could significantly improve the course of pregnancy but also the condition of offspring.