Abstract
BACKGROUND: Thirdhand smoke (THS) is an emerging public health issue, posing risks during pregnancy, including chronic diseases, fetal harm, and cognitive-behavioral disorders in children. This study aims to design, implement, and evaluate an educational intervention to improve the awareness, beliefs, and practices of pregnant women in relation to thirdhand smoke exposure. METHODS: This study, conducted in 2023–2024, evaluates an educational intervention’s impact on pregnant women’s knowledge, beliefs, and practices regarding thirdhand smoke (THS) exposure. It involves 100 pregnant women from four healthcare centers in Isfahan, Iran, selected by geographic zoning and randomly assigned to intervention or control groups (50 per group) via coin toss, with 5% type I error and 80% power. Data collection uses the Beliefs About Thirdhand Smoke (BATHS) questionnaire and a researcher-designed questionnaire on THS knowledge and practices. The study has three phases: Phase 1: psychometric evaluation of questionnaires and pre-test implementation • Psychometric evaluation of questionnaires for validity and reliability: to ensure the validity and reliability of the questionnaires, two groups of pregnant women (20 participants in each group—intervention and control) will complete the questionnaires. In addition, the educational content will be evaluated by a panel of at least 10 experts using indices such as the Content Validity Index (CVI), Clarity and Simplicity Index, Attractiveness Index, and Practicality Index. • Pre-test implementation: awareness, belief, and behavior questionnaires regarding third-hand smoke exposure will be completed by pregnant women attending health centers in Isfahan, with 50 participants in each of the intervention and control groups. Phase 2: design and implementation of the educational intervention Based on the pre-test results, an educational intervention will be designed and implemented. The intervention will be conducted in group sessions, both in-person (individual and face-to-face) and virtually via online platforms. The educational content will include scientific information about the dangers of third-hand smoke, preventive strategies, and behavior change methods. Phase 3: Post-test and analysis: Post-test one month post-intervention using the same questionnaires. Data analysis with SPSS v23 includes t-tests, chi-square, Kolmogorov-Smirnov, and non-parametric tests (e.g., Mann-Whitney, Wilcoxon) for non-normal data. Trial registration: IRCT20250105064282N1 was completed on 08/04/2025. CONCLUSION: This study examines how educational interventions can improve pregnant women’s knowledge, beliefs, and practices about thirdhand smoke (THS). Tailored education, using combined group and individual approaches, can boost awareness of THS risks and encourage protective behaviors. Social support and tobacco control policies in public spaces can further enhance these effects, especially in communities with low awareness of tobacco-related harms.