ABSTRACT Objective: Describing the trajectory and constitution of Obstetric Nursing in seven decades of existence of the Nursing School of the Universidade Federal do Rio Grande do Sul (EENFUFRGS). Methods: Theoretical and reflexive study based on documents and author experience. Data analysis was based on Michael Foucault’s theoretical framework. Results: Analysis identified knowledge and forces that structured and characterized the Arena I: the creation of EENFUFRGS; the Arena II: Obstetric Nursing in graduation; the Arena III: Obstetric Nurses formation, and Arena IV: we are not alone!, highlight the importance of EENFUFRGS in its relationship with other entities. Final considerations: During the 70 years of EENFUFRGS existence, it maintains the vitality of a solid institution in its principles coupled with a youthful in disposition, facing necessary challenges to guarantee quality teaching and practice of Obstetric Nursing.