Objective: to construct conceptual and operational definitions of Nursing Outcomes “Breastfeeding establishment: infant (1000)” and “Breastfeeding establishment: maternal (1001)”. Method: integrative literature review in the following databases: PUBMED (United States National Library of Medicine); LILACS (Latin American and Caribbean Health Sciences Literature); CINAHL (Cumulative Index to Nursing and Allied Health Literature); SciVerse SCOPUS; Web of Science; BDENF (Brazilian Nursing Database) and EMBASE (Excerpta Medica Database). The gray literature was explored to elucidate topics not covered by the articles. Of 3242 articles, 96 were selected to be read in full, and 43 were used for constructing the definitions. Five theses, three dissertations, three books and two manuals were selected. Results: all the results were reviewed. The definitions facilitated the improvement of the content proposed by the Nursing Outcomes Classification, favoring its application in clinical practice and supporting the development of research and teaching. Conclusion: it was proposed to change the definition of the two outcomes, as well as to change the title of one of them to “Breastfeeding establishment: newborn & infant” (1000), modifying seven of its indicators and excluding one. For the outcome related to the mother, it was proposed to modify two indicators and exclude one.