Background of the study:  Mood changes in the early days of postpartum are particularly common. Postpartum blues are a common mental health problem during the early postpartum period. There are many alternative therapies to treat this. However, Music therapy is easy to perform without any risk, and with minimal expenses, it decreases the cortisol level in the bloodstream which causes stress and leads to a decrease in the postpartum blues. The study aims to evaluate the effect of teaching guidelines on pregnant women's knowledge, practices, and stress regarding Postpartum Blues. Material and method: The research design adopted for this study is a quasi-experimental pre-test post-test one-group design. Settings: The study was applied in the antenatal care clinics at Sohag. Subjects: Including 100 pregnant women with a convenient sampling technique was used to select the samples from the previously selected settings. Tools: Tool (I): Structured interview questionnaire: Used to collect data regarding personal and Obstetric data, Tool II: Pregnant women's knowledge regarding postpartum blues, Tool (III): Pregnant women's reported practices regarding postpartum blues, Tool (V): Perceived Stress Scale-10 (PSS-10). Result:  There was a highly statistically significant difference between pregnant women's knowledge regarding postpartum blues pre and post-teaching guidelines implementation (p<0.001**). Before the teaching guidelines implementation, more than three-quarters of pregnant women had unsatisfactory total reported practice scores pre-teaching guidelines implementation regarding postpartum blues which improved, and most of them had satisfactory total reported practice scores post-teaching guidelines implementation. There was a significant reduction in mean post-test postpartum blues scores at P<0.001) post-teaching guidelines implementation than pre-teaching guidelines implementation. Conclusion: Teaching guidelines implementation had positive effects on improving pregnant women's knowledge, practices, and stress regarding postpartum blues. Recommendation: Teaching guidelines implementation regarding the postpartum blues should be taught to pregnant women during the antenatal period to prevent complications associated with these problems.