Background: Higher levels of parental stress have long-term effects on children's health and could lead to dysfunction in the parent-child interaction. Different background factors can be predictors of high parental stress. Aim: The aim of this study was to examine parental stress among Swedish women and identify different factors linked to women's parental stress. Method: About 702 women were recruited to a clinical study and followed up six months after birth. Data were collected by two questionnaires, and 279 women completed the Swedish Parental Stress Questionnaire (SPSQ). Findings: Less than very good mental health and depressive symptoms after birth were strongly associated with parental stress, and the strongest association was found between post-partum depressive symptoms and high levels of stress in the subscale Incompetence. Multiparity was associated with high stress in two subscales, and lower level of education was a protective factor for stress in nearly all subscales. Conclusions: Depressive symptoms and perceived poor mental health post-partum are the most important factors related to high parental stress. The results point to the importance of identifying and supporting mothers with depressive symptoms, since these women have both mental illness and increased stress.