Development of a health literacy scale for nutrition and supplement use among pregnant and postpartum women.

PURPOSE: This study aimed to develop and validate a health literacy scale to assess nutrition and dietary supplement use among pregnant and postpartum women. METHODS: Baker's health literacy model was used as the conceptual framework. Based on a comprehensive review of domestic and international literature, 60 preliminary items were generated across four domains: vocabulary, familiarity, reading comprehension, and numeracy. After two rounds of expert content validity testing and face validity assessment, 42 items were retained. Data were collected from 315 pregnant and postpartum women between March 31 and May 11, 2021, using an online questionnaire administered through Google Forms. Item characteristics and construct validity were examined using Rasch analysis based on item response theory. Concurrent validity and reliability were also evaluated, and 23 items were retained for the final instrument. RESULTS: Exploratory factor analysis supported the unidimensionality of the scale. The Kuder-Richardson Formula 20 coefficient for the 23-item scale was 0.87, indicating high internal consistency. The optimal cutoff score was 12.50, with a sensitivity of 0.61, a specificity of 0.66, and an area under the receiver operating characteristic curve of 0.727, indicating acceptable discriminative ability. CONCLUSION: The developed instrument demonstrated satisfactory criterion validity and high reliability. It effectively distinguished pregnant and postpartum women with high and low levels of health literacy related to nutrition and supplement use and may be used in clinical and community settings to assess health literacy and support tailored educational interventions.