Gestational diabetes involves disorder of glucose metabolism first diagnosed in pregnancy. Obese women undoubtedly have more often complications in reproductive age, such as fertility difficulties, spontaneous and recurrent miscarriages, premature births, and various obstetric and surgical complications related to the course of pregnancy, delivery and puerperium. Children of obese pregnant women are more likely to develop obesity in childhood and adulthood. We analyzed the outcome of 51 pregnancies in obese pregnant women and 50 pregnant women with normal body mass index. All women in both groups were diagnosed with gestational diabetes by the IADPSG criteria. We analyzed gestational age at delivery and mode of delivery, gestational weight gain, presence of concomitant diagnosis of gestational or chronic hypertension, difference in birth weight, and prevalence of hypertrophic newborns. There was no significant difference in gestational age at pregnancy termination and in the mode of delivery. There was a significant difference in gestational weight gain, number of pregnant women with hypertension, neonatal birth weight and number of hypertrophic children. Based on the data presented, we conclude that obesity is an unfavorable factor for pregnancy outcome. It also influences birth weight and fetal hypertrophy, as well as gestational weight gain.