Background:Postpartum depression (PPD) is an important and prevalent disorder that can have short-term and long-term adverse effects on the mother, child, and family. This meta-analysis was conducted with the aim of investigating factors related to PPD in Iran.Methods:This systematic review and meta-analysis reviewed observational studies in Iran. Four Persian language databases (Magiran, IranDoc, ISC, and SID) and four English language databases (ScienceDirect, Scopus, PubMed, and Web of Science) were searched from their inception to September 20, 2023. Google Scholar search engine was used to find relevant sources and complete the search coverage. The process of searching and selecting studies was drawn using the Preferred Reporting Items for Systematic reviews and Meta-Analysis diagram. The strength of the association was summarized using the odds ratio (OR) with 95% confidence intervals (CIs). We used RevMan 5.4 software to analyze the data after extraction.Results:A total of 28 studies involving 11,784 participants were included. The meta-analysis showed that cesarean (OR = 0.77, 95% CI: 0.60, 0.98), history of abortion (OR = 1.48, 95% CI: 1.14, 1.92), unwanted pregnancy (OR = 0.58, 95% CI: 0.45, 0.76), formula feeding (OR = 0.50, 95% CI: 0.39, 0.65), diploma and less education (OR = 1.27, 95% CI: 1.08, 1.48), neonatal hospitalization (OR = 1.77, 95% CI: 1.13, 2.76), more than two deliveries (OR = 0.76, 95% CI: 0.67, 0.86), and low and moderate socioeconomic status (OR = 1.77, 95% CI: 1.34, 2.34) have a significant effect on PPD. Satisfaction of the newborn gender (OR = 0.88, 95% CI: 0.58, 1.33), employment (OR = 1.16, 95% CI: 0.97, 1.40), age (OR = 0.89, 95% CI: 0.58, 1.39), previous depression (OR = 1.76, 95% CI: 0.88, 3.50), and gender of the newborn (OR = 0.82, 95% CI: 0.42, 1.60) did not have a significant effect on PPD.Conclusion:The results of this study showed that many factors influence PPD. Most of these factors can be identified during pregnancy, which shows the importance of screening during pregnancy. Therefore, it is necessary to design and use screening tools to identify predisposing variables for PPD according to the social–cultural characteristics of different populations.