IntroductionStudies have shown that women suffer from depression more than men (1). Among different types of depression, postpartum depression is worthy of significant attention because it not only affects mother's health, but also adversely affects growth and psychological evolution of the newborn (2,3). In many women, child birth is a stress-causing factor which is the stimulus for beginning of an acute depression or its recurrence (4). In fact, the period after the childbirth is the transitional period in which mother faces new roles, models, and relations that she has to adapt to (5). On the other hand, since the energy stored in a mother is lost during puerperium due to fatigue, drug effects, maternity duration, problems caused during the maternity process etc., the mother is subjected to emotional and psychological crises, including depression more than any other time (6). Based on criteria described by the Diagnostic and Statistical Manual of Mental Disorders (fourth edition), postpartum depression is defined as the depression which occurs at the fourth week after the childbirth. This disorder is specified by signs and symptoms including depressed mood, lack of sense of satisfaction from life, irritability, amnesia, repeated dizziness, physical symptoms, ambivalence, negative feeling about the infant, inability to take care of the child, suicide thoughts (7), decreased self-confidence (8), hopelessness and incompetency, sense of guilt, fear and worthlessness (9). According to the family systems theory, any factor that affects one member of a family and causes disorders in their performance within the family system, would inevitably also affect other members of the family, causing disorder in their behavior and performance (10). Prevalence of depression in husbands of the women suffering from this disorder is 5%-20% greater than others (11). Postpartum depression is one of the most important problems that threaten lives of mother, infant and their family (12). This disorder would result in decreased level of healthy relationship between mother and the infant (13), disorder in the growth of the infant (14,15), decreased level of mother health, permanent depression in the women, problems and conflicts in the marital relationships (16,17), increased obsessive-compulsive thought (18) and inability to carry out maternal and marital duties (19). Depressed mothers have lower sense of responsibility and responsiveness towards their infants and have complicated AbstractObjectives: The purpose of this study was to investigate the prevalence of factors affecting postpartum depression in women in the city of Qom, Iran. Materials and Methods: This study was a survey research. The research population included all women who were within 4 weeks postpartum and referred to health centers in Qom. The sample consisted of 120 subjects who were selected by convenience sampling method. Edinburgh Postnatal Depression was the research tool. Once collected, the data were extracted and analyzed using SPSS software and t test. Result...