Objective: The effect of a new, structured group training program on the anxiety reduction in Iranian pregnant women at risk of preterm labor (PTL) was assessed. Design: A randomized controlled clinical trial. Setting: The prenatal care center in the Gynecology Clinic of University Hospital. Population: 72 Iranian pregnant women at risk of PTL with a gestational age of 24–28 weeks. Methods: Several trained research nurses presented group educational counseling sessions for 6 weeks based on the integration of psychological instructions and interactive lectures for the intervened group ( n = 36). Pregnant women in the control group ( n = 36) only received routine pregnancy care. Main Outcome Measures: The completion of pregnancy-related anxiety questionnaire (PRAQ) for Iranian pregnant women at risk of PTL in the intervention (before and after 6-week counseling, and 1-month post-counseling) and control (before, and on the 6 th and 10 th week after the study) groups. Results: There was a significant difference in the mean anxiety score between the intervention (3.45 ± 0.75) and control (3.01 ± 0.34) groups before the group educational counseling sessions. After this intervention, a significant reduction in the mean anxiety scores of intervened pregnant women (2.48 ± 0.32) compared to the control (2.68 ± 0.81) was found. This decrease in mean anxiety score after the 1-month post-counseling was more pronounced than the 6 th week after the study onset ( P < 0.001). Low anxiety scores in the intervention group over time were also maintained. Conclusions: Implementing the group educational counseling sessions is recommended as a complementary, effective, and noninvasive intervention to efficiently control the anxiety in pregnant women at risk of PTL.