Background: Pregnancy and delivery are among the leading causes of mortality, morbidity, and disability worldwide. This study aimed to analyze the effectiveness of an educational intervention based on the health belief model in preventing high-risk behaviors among pregnant women. Methods: This randomized controlled field trial was done in 2015 on 88 pregnant women who referred to two main healthcare centers in Sarbisheh, Iran. Women were purposively recruited and randomly allocated to an intervention and a control group. For data collection, a questionnaire was developed based on the components of the health belief model. Participants completed the questionnaire both before and three months after the intervention. Women in the intervention group were offered three educational and counseling sessions on high-risk pregnancies, prenatal care, and high-risk behaviors during pregnancy. The SPSS software (v. 22) was used to analyze the data by running the Wilcoxon, the Mann-Whitney U, and the Chi-square tests.