RESUMEN
SUMMARY OBJECTIVE: The aim of this study was to perform a cross-cultural adaptation of the Breastfeeding Self-Efficacy Scale in Exclusive Breastfeeding for use in a Brazilian-Portuguese context. METHODS: The cross-cultural adaptation process involved the translation from original English into Brazilian Portuguese by two qualified and independent translators. Both translations were synthesized into a single version that was back-translated into English. An expert committee was created to assess linguistic equivalences, formulating a pre-final version that was tested on ten nursing women attending a maternity hospital. To assess its psychometric properties, a cross-sectional study was carried out. The population consisted of 99 nursing women from a reference maternity hospital in southern Brazil. The scale's stability and internal consistency were measured through Cronbach's alpha. The Pearson's correlation coefficient and the intraclass correlation coefficient between two applications were assessed to ascertain the Breastfeeding Self-Efficacy Scale in Exclusive Breastfeeding-Br scale's reliability. The construct validity was evaluated through exploratory factorial analysis. RESULTS: The Breastfeeding Self-Efficacy Scale in Exclusive Breastfeeding-Br showed a general Cronbach's alpha of 0.849. The test-retest analysis showed a Pearson's correlation coefficient of 0.483 and intraclass correlation coefficient of 0.645. The exploratory factorial analysis showed two domains among the nine items of the Breastfeeding Self-Efficacy Scale in Exclusive Breastfeeding-Br: the functional domain, including six items, and the cognitive domain, including three items, explaining 59.77% of the variance. CONCLUSION: The Breastfeeding Self-Efficacy Scale in Exclusive Breastfeeding-Br was considered adequate for the cultural context and reliable and valid for Brazilian nursing women.