development and validation of an instrument measuring maternal breastfeeding behavior according to the theory of planned behavior

Background: the validity and reliability of measurement instruments are fundamental prerequisites for high-quality research. this study aimed to develop and evaluate the psychometric properties of a newly designed instrument to assess maternal breastfeeding behavior based on the theory of planned behavior (tpb).methods: this cross-sectional study involved the development of an initial 51-item questionnaire derived from a comprehensive literature review of databases including sid, magiran, pubmed, scopus, and sciencedirect. face and content validity were assessed qualitatively through expert panel review and quantitatively using the content validity ratio (cvr) and content validity index (cvi). construct validity was examined using exploratory factor analysis (efa) and confirmatory factor analysis (cfa). reliability was evaluated using cronbach's alpha and the intraclass correlation coefficient (icc).results: quantitative content validity indices were acceptable (cvr = 0.62, cvi = 0.79). exploratory factor analysis identified a six-factor structure — attitude, subjective norm, perceived behavioral control, self-efficacy, intention, and behavior — accounting for 62% of the total variance. the kaiser-meyer-olkin measure of sampling adequacy was 0.82. confirmatory factor analysis supported the factor structure and demonstrated good model fit (χ²/df = 1.18, rmsea = 0.052, cfi = 0.939, gfi = 0.93, agfi = 0.91). the instrument also exhibited strong reliability, with icc values ranging from 0.80 to 0.92 and cronbach's alpha coefficients between 0.80 and 0.93 across all constructs.conclusion: the findings indicate that the tpb-based questionnaire is a valid and reliable instrument for assessing maternal breastfeeding behavior and is suitable for use in future research and clinical practice.