Background & Aims: Anxiety during pregnancy and fear of childbirth is seen as common problems in Primiparous women. Anxiety and fear during pregnancy are sometimes considered a natural mechanism that prepares the expectant mother for pregnancy and the accompanying changes, but the intensification of worry and anxiety can take the form of illness and affect the mental health of pregnant women. More than 80 percent of women with low)risk pregnancies experience some degree of anxiety and fear of childbirth, and in 6 to 10 percent of cases, this anxiety and fear cause severe debilitating complications in pregnant women. There are several treatment methods to reduce the symptoms of anxiety and fear of childbirth. One of the effective treatment methods is behavioral activation therapy. This treatment method is one of the third-wave psychotherapy methods that increase the behaviors that increase the contact of the person with the reinforcing connections of the environment. In this treatment method, the patient is taught to use an alternative and adaptive coping model in dealing with annoying and frustrating environmental conditions and to react with an active behavior instead of avoidance. Research findings have shown that excessive activity of the inhibitory system leads to anxious personality traits, high sensitivity to threatening stimuli, and anxiety-related behaviors such as worry and fear. The results of some studies confirm the existence of a relationship between inhibition systems and psychiatric disorders such as depression, fear, and anxiety, but few studies have investigated the effect of this method on reducing anxiety and fear in Primiparous women. Another way to reduce fear and anxiety is to use a calm tone. Using a relaxed tone during pregnancy as a suitable method to calm the mind and mind, focus attention on the fetus, positive imagery towards pregnancy, and increase the relationship, and attachment of mother and fetus has been desired by the researchers. In relaxation training, by using breathing techniques, special verbal stimuli, and mental relaxation during the treatment of clients, people are helped to reduce their stress and achieve calmness in their bodies and mind. achieve Correctly performing relaxation exercises improves a person's blood circulation and reduces tension, anxiety, and depression by creating a positive attitude and improving brain function, and increasing people's cellular energy and confidence by relieving their anxiety. Relaxation methods are also known to be effective in many situations such as pain, childbirth, anxiety, and insomnia during pregnancy, and it causes a person to gain the power to control his emotions and behaviors. Considering the great importance of fear and anxiety and their effects on the mental health of Primiparous pregnant mothers, this research aims to determine and compare the effect of educational interventions on the effectiveness of behavioral activation and relaxation in reducing anxiety and fear of childbirth in women. Prenatal care was performed in the hospitals of Karaj city. Methods: The current research was a semi-experimental study with a control group in terms of practical purpose and research design. The statistical population of the research included pregnant women with first births in Karaj in 1400. 144 Primiparous pregnant women referring to Shahid Madani Hospital in Karaj were randomly selected and placed in two groups of behavioral activation and relaxation technique (48 people in each group) and a control group (48). For the experimental group, a training session on behavioral activation and calm tone was implemented, and then a researcher-made questionnaire was used to collect data on the effectiveness of the training on the scores of anxiety and fear of childbirth. The reliability of the questionnaires was confirmed using Cronbach's alpha of 0.78 for anxiety and 0.71 for fear. Descriptive and inferential statistics were used for data analysis using SPSS version 21 software. Results: In this research, 144 Primiparous pregnant women were studied in two groups of behavioral activation and relaxation techniques (48 in each group) and the control group (48). The studied groups had no statistically significant differences in terms of the variables of gestational age and the interval between marriage and first pregnancy. The results showed that after the intervention, the anxiety and fear of childbirth of Primiparous pregnant women in the intervention groups decreased significantly, but no significant statistical difference was observed in the control group. Conclusion: It seems that behavioral activation training and relaxation training can help Primiparous pregnant women to recognize, despite the automaticity of many bodily responses, they can identify them and reduce the anxiety and fear of childbirth. According to the results of relaxation and behavioral activation during pregnancy, it can be considered as a suitable method to reduce anxiety and fear of pregnancy. This study showed that the designed intervention has significant positive effects on reducing the anxiety and stress of pregnant women. Therefore, it is suggested that a series of training in the form of behavioral activation and relaxation should be included in the care programs of pregnant women. The method of reducing fear and anxiety based on calm tone and behavioral activation due to having conscious and non-judgmental techniques can have beneficial effects in improving fears and worries during pregnancy. Considering the simplicity and availability of training in behavioral activation techniques and body exercises, it is suggested the presence of a supportive person such as a life partner, female relatives, and a private midwife; by doing these interventions, they can increase the satisfaction of the birth experience and the feeling of comfort and reduce the fear and anxiety. Considering the limited number of people and the duration of the interventions in this research, it is suggested that this training be carried out with a longer duration and on a larger sample size of pregnant women. The effect of this research with the effect of other therapeutic and psychological methods on the dependent variables of this research should be compared and investigated in practice. Also, in order to evaluate the effect of the passage of time on the retention of educational achievements, it is suggested that researchers consider follow-up courses in future research. Considering that one of the limitations of the present study was the use of a questionnaire in the data collection process, it is suggested that another study be conducted with other tools (observation and interview) to investigate the level of anxiety and fear of childbirth in Primiparous women. [ABSTRACT FROM AUTHOR] more...