Background & Objective: Appropriate physical activity help to promote women's health during pregnancy. Providing appropriate educational programs for pregnant women seems to be necessary. This study was carried out to assess the effectiveness of a group educational program on pregnant women's physical activity.

Methods & Materials: This clinical trial was conducted among 280 nulliparous women. The participants were randomly divided into two experimental and control groups. Women in the experimental group participated in eight 90-minute group-based educational classes. Those in the control group received routine care. Data were collected at baseline and at the end of the educational program. Data were analyzed using the Chi-squared test and the t-test in the SPSS.

Results: There were no statistical differences on age, body mass index, education level, employment status, and physical activity between the two groups at baseline. The physical activity score was more in the experiment group (37.38±14.89) in compare with the control group (13.7±11.12) after the intervention (P<0.001).

Conclusion: The group-based educational program seems to promote physical activity during pregnancy. These kinds of programs should be implemented in prenatal clinics.