Objectives: understand the structure and content of the maternal representations of Mexican teenagers during their first pregnancy. Methods: a study was carried out with qualitative methodology based on the concept of maternal representation and the theory of social representations with 30 adolescents who attended prenatal control at the Civil Hospital of Guadalajara "Fray Antonio Alcalde", in Jalisco, Mexico. The participants were interviewed with the consent of their tutors. Classical content analysis techniques were used to obtain codes and thematic categories to develop a conceptual map that explains maternal representations. Results: the maternal representation was identified: "Pregnant but reunited, a legitimated bad decision", which was composed of social meanings towards adolescent pregnancy, family dynamics, expectations towards motherhood, and the feelings experienced by the adolescent during the pregnancy. The content of the representations was heterogeneous for most of the identified categories; however, it is identified that the desire for pregnancy guides the expectations of the adolescent about her future way of being as a mother. Conclusions: the desire of women for pregnancy, the level of participation of the couple, and the social meanings of adolescent pregnancy, have an outstanding role in the development of models of maternal representations.