Objective: The aim of this study was to reveal pregnant women's beliefs about third-hand smoke and their exposure to tobacco smoke. Methods: The population of this cross-sectional study consisted of patients attending the obstetrics and gynaecology outpatient clinic of the hospital in Samsun, a province of Turkey on the Black Sea coast (annual average 4,000 pregnant women). The minimum sample size of the study was determined as 350 at a confidence interval of 95%, prevalence of 50% and margin of error 0.05. The study data were collected with the personal information form used to determine the personal characteristics of the participants, and the Beliefs about Third-Hand Smoke (BATHS-T) scale. The data were analysed in the SPSS 25.0 program using the descriptive statistics and multiple regression analysis.Results: The mean age of the participating pregnant women was 26.84 ± 4.372 years. Of them, 48.4% were high school graduates and 86% did not work. Their mean gestational age was 29.85 ± 9.238 weeks, and 69.8% of them were in the third trimester. Of them, 9.8% were smokers, and the average number of cigarettes they smoked per day was 6.97 ± 4.931. The mean score they obtained from the BATHS-T scale was 3.79 ± 0.859. There was a significant relationship between the mean score obtained from the BATHS-T scale and the variables such as education and smoking status. As the level of education increased, exposure to third-hand smoke decreased (p < 0.05). The mean score the smoking pregnant women obtained from the BATHS-T scale was lower than that of the non-smoking pregnant women.Conclusion: High level of education decreases exposure to third-hand smoke. Belief in third-hand smoke is an important factor affecting pregnant women's smoking habit.