Summary Objective: The aim of the study was to estimate the effect of maternal obesity on pregnancy course, delivery and newborn well-being. Material and methods: Data about women who delivered in PMMH was analyzed and obese pregnant women (pre-pregnancy BMI ≥30) were included in the study group; the rest of the mothers constituted the control group. The pregnancy course, labor and delivery, and newborn well-being were taken into consideration. Results: 4648 women were found in our delivery database, among them 208 (4.48%) were classified as obese. In this group, pregnancy-associated hypertension was common, either non-proteinuric one (8.65% vs 2.39%, p=0.001) or preeclampsia (4.81% vs 1.58 %, p<0,05). There were also more cases of gestational diabetes mellitus requiring insulin therapy (9.62% vs1.48%, p<0.001) and polyhydramniosis (4.81% vs 2.11%, p<0.05) than in case of controls. The mean gestational age at delivery and newborn general health (estimated by Apgar score, mean umbilical cord pH and the incidence of cases with pH ≤7.10) were similar in both groups. The mean birthweight (3266g vs 3100g, p<0.05) and the incidence of macrosomia (20.19% vs 5.69%, p<0.001) were significantly higher in the study group. The delivery mode was comparable in both groups, with the marked tendency towards higher incidence of elective cesarean sections in case of obese mothers (27.88% vs 19.90%, p=0.01). Conclusion: Maternal obesity is a significant perinatal risk factor; with pregnancy-associated hypertension and gestational diabetes requiring insulin therapy in obese mothers and macrosomia in newborns as most common complications.