Although the rates of adolescent pregnancies appear to have dropped according to the World Health Organization (WHO), the decrease in the age of the first menarche and better nutrition seems to contribute to the otherwise high rate of adolescent pregnancy worldwide, despite the efforts of different organizations to improve upon this trend. We conducted a population-based retrospective cohort study from January 2015 to December 2021 using our hospitals’ database. We totaled 2.954 adolescent and 6.802 adult pregnancies. First, we compared younger adolescents’ outcomes with those of older adolescents, as well as with adolescents aged between 18 and 19 years old; secondly, we compared adolescent pregnancies with adult ones. We detected higher percentages of cephalo-pelvic disproportion (43.2%), cervical dystocia (20.7%), and twin pregnancy (2.7%) in underage adolescents compared with 32%, 14.1%, and 1% in older underage adolescents, respectively, and 15.3%, 3.1%, and 0.6% in older ones. As teens became older, the likelihood of malpresentations and previous C-sections rose, whereas the likelihood of vaginal lacerations declined. When comparing adolescents with adult women, we found more cases that required episiotomy (48.1% compared with 34.6%), instrumental delivery (2.1% compared with 1%), and cervical laceration (10.7% compared with 8.4%) in the adolescent group, but the rates of malpresentation (11.4% compared with 13.5%), previous C-section (13.9% compared with 17.7%), and placenta and vasa praevia (4.5.6% compared with 14%) were higher in the adult women group. Adolescent pregnancy is prone to being associated with higher risks and complications and continues to represent a challenge for our medical system.