ABSTRACT
Background@#Childbearing is the most important determinant of population fluctuations, and its study is more important than other population phenomena. Owing to the lack of a valid questionnaire based on the extended theory of planned behavior, this mixed-method study was conducted to determine the validity and reliability of a questionnaire designed to examine related belief-based factors on the intention to bear children in Iranian society. @*Methods@#This study was conducted in two phases in Hamadan city, western Iran, in 2021. Phase 1 consisted of an extensive literature review and a qualitative study using a directed content analysis approach to generate an item pool. Psychometrics were measured in phase 2, including content, face, and construct validity. Reliability was assessed based on internal consistency and stability. The collected data were analyzed using IBM SPSS and AMOS ver. 24.0. @*Results@#Mean content validity ratio and content validity index were 0.7 and 0.85, respectively. Exploratory factor analysis of the 32 items identified an eight-factor solution. These factors jointly accounted for 79.1% of the observed variance in the outcome variables. Confirmatory factor analysis indicated a good fit for the data. The internal consistency based on Cronbach’s α was 0.85 (0.71–0.93). In addition, stability was confirmed using the test-retest method and intraclass correlation coefficient (0.74–0.94). @*Conclusion@#The designed questionnaire is a valid and reliable instrument for evaluating related belief-based factors on the intention and behavior of childbearing among married men and women in Iran.