Maintaining a health-promoting lifestyle is defined as controlling certain behaviors and selecting appropriate behaviors in the daily life for one's own health (1). Healthpromotion behavior is a multifaceted model of perception, self-initiated action or practice (2). It is a response to World Health Organization's (WHO's) goal of "health for all" (3). According to Pender, health promoting lifestyle behaviors include nutrition, exercise, stress management, health responsibility, spiritual improvement, and interpersonal relations (4). During pregnancy, health-promoting lifestyle leads to a reduction in risk factors and an improvement of infant's health (3). Nowadays, the mortality of pregnant women is one of the key indices of health in all countries. This has both direct and indirect impacts on pregnancy outcomes. The health of pregnant women-as a vulnerable groupis of particular importance in the healthcare systems (5). In fact, a large number of physiological, psychological, and social changes occur during pregnancy. The mother's adjustment to these changes is highly important (6). Rubin stated that it is necessary for pregnant women to acquire 4 maternal duties, the most important of which is seeking for safety. Therefore, the following health-promoting behaviors are essential for giving birth to a healthy infant (2). Although a great body of evidence exists in respect of the benefits of health promoting behaviors, getting people to adopt a healthy lifestyle is challenging (7). Unfortunately, many women are against the application of healthy behaviors during pregnancy. For example there is a decrease in the level of physical activity as pregnancy progresses (8). Physical activity on pregnancy has many positive effects on the health of the mother and foetus (9). These include better health-related quality of life (10), reduction of stress and depressive symptoms (11), less delivery pain, lower rate of cesarean delivery, lower risk of obesity, selfefficacy, and better body image (12). Overall, pregnant women faced the challenge of continuing physical activity during pregnancy (13). Self-efficacy has been defined as an individual's perceived belief in having the ability to benefit from one's personal sources of motivation and organization and acts to reach a specific goal (14). Self-efficacy is a strong predictor of health behaviors, and also initiation and maintenance of exercise during pregnancy (13). Bandura indicated that theory of self-efficacy provides a convincing explanation