Adolescent pregnancy remains a health issue worldwide also in developed countries, since it has been associated with adverse maternal and neonatal outcomes. Some data suggest that very young adolescents have higher risk, likely due to immaturity. Therefore, we aimed to assess the influence of maternal age on complications during gestation and labor in pregnant women between 13 and 19 years of age. In particular, we evaluated the possible association between maternal age and obstetric, fetal and labor complications. This is a retrospective, observational and exploratory study conducted at Hospital Universitario La Paz (HULP, Madrid, Spain). The clinical history of 279 women who delivered between 2013 and 2018 was analyzed. Maternal age and the presence of maternal, fetal and labor complications, as well as risk of postpartum depression and breastfeeding intention, were recorded. General regression models were used to analyze the contribution of maternal age on each complication. The percentage of adolescent pregnancies at HULP between 2013 and 2018 was 0.9%. The risk of all the maternal complications analyzed decreased significantly with every year of age of the mother (hyperemesis, lower back pain, anemia, gestational diabetes mellitus, and threat of premature labor and premature rupture of membranes). Every year of maternal age decreased 0.8-fold [0.8; 0.9] the prevalence of fetal complications and also reduced the risk of C-section, postpartum hemorrhage and obstetrical hysterectomy. Furthermore, higher maternal age increased 1.1-fold [1.0; 1.2] the breastfeeding intention. In conclusion, young adolescents are at higher risk of complications during pregnancy and labor.