Objective: To evaluate the relationship between pregestational obesity and maternal and fetal outcomes in pregnant adolescents. Methods: Cross-sectional study conducted among puerperal teenagers of a university hospital in Southern Brazil. Structured questionnaires on sociodemographic and obstetric data were applied. Results: We evaluated 500 puerperal adolescents with a mean age of 17.77 ± 1.36. Of these, 31.2% (n=156) had pregestational weight excess. Pregestational weight excess was significantly associated with gestational hypertension (p=0.037) and diabetes (p=0.045), cesarean delivery (p=0.040), and lower adherence to prenatal care (24.7%, p=0.007).