Introduction: Most Western women work during their reproductive years, but past research has often neglected the influence of work-related factors on postpartum health. Especially postpartum depression (PPD) puts an enormous psychological burden on mothers. Therefore, this study aims to investigate the prospective impact of precarious working conditions and psychosocial work stress (such as work-privacy conflict and effort-reward imbalance at the job) during pregnancy on symptoms of maternal PPD. Methods: In the prospective-longitudinal cohort study DREAM ( DR esdner Studie zu E lternschaft, A rbeit und M entaler Gesundheit), N = 587 employed women were questioned about their work during pregnancy and mental health 8 weeks after delivery. Results: Multiple regression analyses revealed that work-privacy conflict, low reward at work, and precarious working conditions significantly predicted symptoms of PPD, even when controlling for lifetime depression, anxiety, education, parity, and age. Conclusion: Our results indicate that psychosocial work stress and precarious working conditions have important implications for maternal peripartum mental health and might act as prospective risk factors for PPD even during the period of maternal leave. Hence, preventative measures targeting work life need to be investigated in more detail.