Health system interventions to floods and heatwaves for maternal and child health services: a realist-informed systematic review protocol.

introductionFloods and heatwaves are becoming more frequent and intense and can disrupt routine maternal and child health (MCH) services. Previous reviews have not systematically examined how context and mechanisms may shape adaptation outcomes. This realist-informed systematic review examines how, why and under what conditions interventions support access to, utilisation of and continuity of routine MCH services during flood and heat events. METHODS AND ANALYSIS: The search strategy was developed by integrating terms from 17 related reviews, refined with the author team and checked by an experienced London School of Hygiene & Tropical Medicine librarian. The initial database search was conducted on 16 May 2025 and the search was updated on 30 April 2026. Eight databases were searched: Web of Science, Ovid MEDLINE, EMBASE, Global Health, EconLit, GreenFILE, CINAHL and ProQuest Environmental Science & Public Policy. Records published between January 2000 and April 2026 were eligible. Search results were imported into EndNote and deduplicated. Title-and-abstract screening and full-text assessment were conducted independently by two reviewers for the initial search and are ongoing for the updated search, with ASReview being used to prioritise records during title-and-abstract screening. Data extraction across the full review evidence base remains ongoing using a structured template covering study context, intervention characteristics, mechanisms, outcomes, costs and implementation conditions. Study settings will be classified by country income group, health system context and Köppen-Geiger climate zone to compare evidence across settings and, where appropriate, to identify possible climate analogues for exploratory, context-specific assessment. Climate-zone similarity will not be used to infer intervention transferability or future effectiveness. The synthesis will be guided by the WHO Climate-Resilient Health Systems framework, Meadows' leverage-points framework and realist-informed C-M-O reasoning. Interventions will be grouped to identify where they operate within the health system and which health system components and vulnerabilities they address. Findings will be reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance. ETHICS AND DISSEMINATION: Ethical approval is not required because the review uses published literature and does not involve human participants. The findings will be disseminated through a peer-reviewed systematic review publication. They will inform the design, improvement and scaling of interventions intended to maintain routine MCH services and strengthen health system resilience to floods and heatwaves across diverse settings. REGISTRATION DETAILS: The review was not prospectively registered with PROSPERO.