To evaluate physical activity of pregnant women before and after ACOG guideline study. Four hundred and eighty-five pregnant women enrolled in this before-after study. They were asked to study ACOG guideline. A structured questionnaire filled by women at first visit and the last visit in the prenatal clinic.Type, frequency, duration and anxiety about doing exercises during pregnancy period. Before education, 411 did exercises before pregnancy onset, among them, 346 were walking out and 65 did light exercises such as aerobics. After studying the protocol, 434 (89.4%) did walking during pregnancy period in comparison to 71% who did walking before pregnancy (P<0.001). Forty two (56.7%) out of 74 who had not done sport before, went for walking after the protocol reading, and nine continued not doing exercise. Among 74 participants who had not done exercise before the protocol reading, 16 (21%) were doing exercise three times a week and 11 (14%) changed their habit to daily exercise practice (P<0.001). Forty percent (195 women) were anxious about doing exercise during pregnancy before guideline study, while 116 reported that after the protocol reading, they had no anxiety about doing exercises during pregnancy (P<0.001). Guidelines providing information about physical activity during pregnancy will help pregnant women to do exercise during pregnancy with convenience and less anxiety.