examining exercise behavior beliefs of pregnant women's in second and third trimester: using health belief model

background: although the need for theory-based designs, evidencesexploringexercisingeffects during pregnancy is limited by non-theoretical and cross-sectional assessments. this study aimed to prospect­ively examine women’s exercise behavior from their second to third pregnancy trimester using the health belief model (hbm).   material and methods: this was a randomized controlled trial in which 100 pregnant women (50 individuals in each group of control or intervention) with gestation age of 20 weeks or more were examined. just the intervention gr­oup participated ineight40-minuteexercise classeswith15-day interval between each class. the control group received only routine prenatal care. the researcher- made questionnaires for general demographic characteristics, and variables of health belief model (hbm) regarding doing exercise during pregnancy were completed at two time points of initial of the study and follow up . descriptive/ analytical statistics were applied to analyze the variables using spss version18.  results: the mean gestational age for intervention and control group were 27.40±5.39 and 26.26±5.31 weeks respectively. despite similarity of two groups at initial of the study in terms of all studied variables, , all hbm constructs in intervention group were significantly higher than control group after intervention (all p value ≤ 5%). conclusion: this study revealed that the educational program based on hbm could provide the pregnant women with a conceptual framework to improve the beliefs of pregnant women regarding exercise doing.