Postpartum depression is a global mental health problem affecting 13 million women worldwide each year . It is defined as minor or major depression that occurs up to one year after birth and is estimated to affect 5 to 25% of mothers who have just given birth . Postpartum depression, often associated with periodic depressive episodes, is characterized by emotional lability, guilt, dysphoria, disorientation, and suicidal thoughts and can persist for a long time. Postpartum depression is recognized as an official diagnosis by the World Health Organization's International Classification of Disorders, 10th revision (ICD-10) and the Diagnostic and Statistical Manual of Mental Disorders. While ICD-10 reports that the most critical period for diagnosing postpartum depression is within six weeks after birth, the American Psychiatric Association reported that episodes of postpartum depression can begin within four weeks after birth. Postpartum depression can also turn into permanent and long-term depression, which can increase the likelihood of recurrent episodes of depression in subsequent pregnancies. This is supported by evidence that women with a history of depressive illness are more likely to develop postpartum depression. Postpartum depression can cause negative consequences not only on the mother but also on the newborn and the whole family. Postpartum depression, in particular, has significant effects on mother-infant attachment; It also has negative effects on the mother learning how to care for her baby and transitioning into the parenting role. Postpartum depression can lead to early cessation of breastfeeding or breastfeeding problems; It may also cause the use of preventive health services and vaccination rates in children to be low. Impairments in social participation and emotional regulation, increased negative emotionality, and high cortisol reactivity may be observed in babies of mothers with depression.

During the postpartum period, not only mothers but also their babies may show some behavioral reactions. One of these is crying. There are many possible causes of crying problems in babies, but none of them are certain. It has generally focused on conditions that cause excessive crying in the baby, such as immaturity of the intestinal flora, cow's milk allergy and intestinal microbiota composition. Many studies have raised the question of whether the cause may lie in maternal factors. Crying problems in babies have been associated with low maternal age and education level. Some researchers agree that crying problems arise from the complex mother-infant dyad, and it is well known that maternal postpartum depression and infant crying influence each other . Systematic reviews on this topic have generally found associations between the mother's mental problems (stress, anxiety, or depression) during pregnancy and the baby's regulatory problems, including crying.

The main goal in the postpartum period is to maintain the well-being of mother and baby. However, if a depression is experienced during this period, the main goal is to take action to reduce its severity. Postpartum depression is a specific psychological disorder for which preventive interventions can provide dramatic benefits. In their meta-analysis study by It has been stated that practices such as cognitive behavioral therapies, social support groups, psycho-educational training, physical exercises, yoga, and lack of nutritional supplements are interventions that can be used to reduce the severity of postpartum depression..

Exercise is a potentially promising method to prevent postpartum depression. Since the aim of exercise is to improve or maintain one or more aspects of physical fitness, it is defined as a planned, systematic, repeated and purposeful action.Previous studies have provided compelling evidence regarding exercise in the postpartum period. It has been reported that exercises performed in the postpartum period provide psychosocial well-being, less anxiety and depression, better cardiovascular adaptation, body fat/weight control, less bone loss due to breastfeeding and less stress incontinence, and strengthen the bonding between mother and baby.

Studies generally point to the importance of regular exercise in the postpartum period. However, the number of women exercising in the postpartum period is limited, and lack of access to affordable and appropriate activities is a perceived barrier to exercise. The increasing number of mobile-based applications in recent years offers affordable and accessible exercise applications. These apps use a variety of features, from tracking exercise activity to providing motivational messages. However, what is known about whether exercise practices improve health outcomes and, if so, the mechanisms of these effects is limited. Therefore, there is a need for more studies in this important area to determine the effects of exercise using new technologies as an alternative to face-to-face exercise programs, especially for women living in rural Türkiye and with limited access to health services.

Women who give birth in Türkiye are followed up in the hospital for 24 hours and then followed up three times during the postpartum period at home or in Family Health Centers (FHC) within the scope of health services. Health professionals have a unique duty to follow up women in the postpartum period, identify women at risk for depression, and encourage mothers to use preventive practices such as exercise. It is very important for midwives and nurses to explain mobile-based exercise programs to prevent the development of depression, especially to women living in rural areas, in the postpartum period, to persuade women to participate in these programs, and to perform exercises regularly under the supervision of doctors and physiotherapists in terms of protecting the health of women and their families. Therefore, the aim of this study is to determine the effect of a mobile-based exercise program applied to women giving birth in rural areas on reducing the severity of postpartum depression, mother-baby bonding, and baby crying behavior.