Postpartum depression (PPD) is prevalent among women in Kenyan informal settlements, highlighting a critical public health issue requiring targeted interventions. A comprehensive search strategy was employed to identify relevant studies from databases like PubMed and Cochrane Library, with data extraction using predefined criteria. Mobile mental health support services showed a moderate longitudinal engagement rate (65% of participants continued use over six months), suggesting potential for sustained intervention effectiveness. Despite promising initial results, further research is needed to validate and optimise mobile PPD interventions in Kenyan informal settlements. Future studies should focus on scalability, cost-effectiveness, and participant satisfaction to enhance the impact of mobile mental health services. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.