OBJECTIVE: To explore linkages between water, sanitation and hygiene (WASH) and maternal and perinatal health via a conceptual approach and a scoping review. METHODS: We developed a conceptual framework iteratively, amalgamating three literature-based lenses. We then searched literature and identified risk factors potentially linked to maternal and perinatal health. We conducted a systematic scoping review for all chemical and biological WASH risk factors identified using text and MeSH terms, limiting results to systematic reviews or meta-analyses. The remaining 10 complex behavioural associations were not reviewed systematically. RESULTS: The main ways poor WASH could lead to adverse outcomes are via two non-exclusive categories: 1. 'In-water' associations: (a) Inorganic contaminants, and (b) 'water-system' related infections, (c) 'water-based' infections, and (d) 'water borne' infections. 2. 'Behaviour' associations: (e) Behaviours leading to water-washed infections, (f) Water-related insect-vector infections, and (g-i) Behaviours leading to non-infectious diseases/conditions. We added a gender inequality and a life course lens to the above framework to identify whether WASH affected health of mothers in particular, and acted beyond the immediate effects. This framework led us to identifying 77 risk mechanisms (67 chemical or biological factors and 10 complex behavioural factors) linking WASH to maternal and perinatal health outcomes. CONCLUSION: WASH affects the risk of adverse maternal and perinatal health outcomes; these exposures are multiple and overlapping and may be distant from the immediate health outcome. Much of the evidence is weak, based on observational studies and anecdotal evidence, with relatively few systematic reviews. New systematic reviews are required to assess the quality of existing evidence more rigorously, and primary research is required to investigate the magnitude of effects of particular WASH exposures on specific maternal and perinatal outcomes. Whilst major gaps exist, the evidence strongly suggests that poor WASH influences maternal and reproductive health outcomes to the extent that it should be considered in global and national strategies.