Evidence gap map of the relationship between blue and green spaces and pregnancy outcomes

Over the past decade, research on the relationship between green and blue spaces (GBS) and pregnancy outcomes has grown. However, questions remain about the optimal focus for primary and review studies. To address this, we developed an evidence gap map (EGM) to systematically analyze the literature on GBS exposure and pregnancy outcomes. We identified 13 reviews and 77 primary studies from databases including MEDLINE, EMBASE, PsycInfo, Web of Science, and Maternity & Infant Care. Results were presented through narrative synthesis, complemented by the EGM and network graph.The EGM indicates that primary studies predominantly examined the association between green space quantity and infant health outcomes, using NDVI to assess green space exposure and fetal growth as the primary metric. Only eight studies explored blue space. Most studies had cross-sectional design, originated from high-income countries, and conducted in urban settings, considered place and the socio-economic status of PROGRESS-plus elements, but social capital exploration was limited. Investigations into intersectionality were scarce. The review studies included a similar set of individual studies. We identified 35 individual studies not included in reviews, leaving room for a new review. Further research on blue space and diverse green space measures is important for generating policy-relevant evidence.