The aim of this study was to analyze the relationship between Parenting Stress and Posttraumatic Stress Symptoms (PTSS) to verify whether specific post-partum symptoms of Intrusion, Avoidance and Hyperarousal contribute to explaining mothers’ stress in performance of parenting tasks. Our hypothesis was that the mothers’ posttraumatic post-partum symptoms at three months contribute to explain parenting stress (PSI) in raising children at 18 months The sample was of 53 mothers (mean age =30,92; SD= 4,63) followed from three months (T1) to eighteen months postpartum (T2). At T1 and at T2 the Perinatal posttraumatic Questionnaire and the Parenting Stress Index-SF were administered to evaluate traumatic post-partum symptoms (PTSS) and the stress of being parent. The data show that avoidance symptoms experienced in the first three months have a significant impact on parental distress in the long term; an impact which is stronger than the stress as parent present at three months. The perception of having a difficult child is sustained both by the hyperarousal symptoms and by the corresponding perception of having a difficult child present at three months.