The aim of this study is to investigate the effect of theory-based educational intervention on behaviors of prenatal care in pregnant women referred to health centers in Iranshahr. This is an interventional and randomized study, carried out on 90 pregnant women referred to health centers in Iranshahr. Inclusion criteria were first pregnancy, wanted pregnancy, monogamy, aged between 18 and 35 years old, having health care records and gestational age less than 14 weeks; exclusion criteria included emigration, abortion, absence of the participants in the training sessions and require special care. Participants Were randomized in two groups. Four the intervention group, four sessions of 60 minutes was hold based on the theory (HBM and social support). Control group did not receive any intervention. Before the intervention, immediately after intervention, 3 and 6 months after the intervention, questionnaires were completed by the participants. The tool for collection of data was a questionnaire designed according to health belief model, social support, knowledge and behavior. The primary outcomes of the study include: to determine average scores of Structures of health belief model, social support and prenatal care and secondary outcomes included: to determine birth weight.