Maternal exposure to acute and chronic heat stress predicts multiple adverse birth outcomes with long-term impacts, but pathophysiological pathways remain undefined. West Africa is particularly affected by extreme heat. This project seeks to describe the physiological, biochemical and structural changes in pregnancy due to heat stress. Five integrated work packages are proposed. WP1 will synthesise global evidence for human and non-human primate maternal responses to heat exposure in pregnancy. WP2a will employ environmental chamber studies (FAME Lab Athens) to determine heat stress thresholds for acute maternal, fetal, and materno-placental physiological stress accompanied by a simplified heat-chamber protocol in The Gambia (WP2b). WP3 will be a longitudinal cohort study of 762 pregnant women conducted across 3 heat gradient environments in The Gambia. Outcome measures include maternal physiology & sleep quality (wearable device), materno-placental interface (placental blood flow), pregnancy outcomes and newborn neurobehaviour. WP4 will use placenta samples collected in WP3 to assess the impact of heat stress on placental structure, function and molecular changes. WP5 will use Gambian community workshops to co-design adaptation strategies building on evidence from WPs1-4. This project will build local research capacity, foster international collaborative links and engage communities, key stakeholders and policy makers.