Development and Psychometric Testing of the Breastfeeding Knowledge Scale (BKS) in Brazilian Healthcare Students

Breastfeeding is recognized as a cornerstone of maternal and child health, yet health professionals frequently report insufficient knowledge to provide effective support. Strengthening the evaluation of educational outcomes in health professions training is therefore essential to improve clinical practice and patient care. This study aimed to develop and validate the Breastfeeding Knowledge Scale (BKS), a tool to assess breastfeeding-related knowledge among health professions students in Brazil.

This study followed COSMIN guidelines. Concept elicitation was conducted through workshops with experts and students to identify relevant domains of breastfeeding knowledge. A pilot study, including cognitive interviews with students, evaluated the comprehensibility and comprehensiveness of items. Content validity was assessed with both students and a multidisciplinary panel of professionals using the content validity index (CVI) and content validity coefficient (CVC), complemented by qualitative feedback. Psychometric testing included exploratory factor analysis (EFA) to evaluate structural validity and guide item reduction, followed by assessment of internal consistency with Cronbach's ⍺, calculated only after confirming the unidimensionality of each subscale.

The concept elicitation process yielded five thematic clusters that were reorganized into three broader domains: Biological aspects of lactation, Policy and Sociocultural Context and Clinical Management (including complementary feeding). After iterative refinement and EFA, the instrument was reduced to 40 items. The final version was administered to 143 students. Internal consistency was excellent for the overall scale (Cronbach's ⍺ = 0.910) and strong for each domain (biological = 0.810; policy and sociocultural context = 0.790; clinical management = 0.796). These results supported both structural validity and reliability of the BKS.

The BKS is a valid and reliable instrument for evaluating breastfeeding-related competencies in health professions students. By providing a comprehensive and psychometrically sound measure, it enables rigorous evaluation of training adequacy, supports curriculum improvement and ultimately contributes to strengthening clinical practice and breastfeeding outcomes.