Investigating environmental heat exposure and its effects on maternal and fetal health in rural Northern Ghana (Physio-HeMAB Study): a study protocol for a cluster randomized trial

Background: Climate change increases the frequency and intensity of heat events. Previous studies have established a correlation between heat exposure and adverse pregnancy outcomes, including preterm birth, stillbirth, and other maternal and fetal health complications. However, evidence on the physiological pathways underlying heat strain during pregnancy and on whether heat adaptation strategies can modify these responses remains limited, particularly in low-resource settings. This study aims to assess the effects of environmental heat exposure on maternal and fetal physiological responses among pregnant women exposed and unexposed to a heat adaptation strategy. Methods: Physio-HeMAB is an interventional, cluster-randomized study hosted by the Health and Demographic Surveillance System in Navrongo, Ghana. This study integrates: (i) high-resolution environmental monitoring including Wet-Bulb Globe Temperature at household level and Universal Thermal Climate Index environmental data at regional level; (ii) continuous maternal physiological assessment via wearable devices measuring heart rate, heart rate variability, core body temperature, physical activity, and sleep; and (iii) fetal health assessments, including fetal heart rate and Doppler indices. This multimodal framework supports detailed assessment of how varying levels of environmental heat exposure relate to maternal physiological changes and fetal health indicators. Descriptive and multivariable statistical methods will be used to analyze the data. Discussion: A better understanding of the physiological mechanisms of heat strain during pregnancy, and an evaluation of whether targeted adaptation strategies can mitigate its effects, are essential for protecting maternal and neonatal health. This Physio-HeMAB study integrates individual-level physiological responses to environmental heat exposure and heat adaptation strategies. This approach strengthens the evidence for developing context-specific and gender-responsive public health interventions. Trial registration: This study was registered in the Pan African Clinical Trials Registry as PACTR202601761543866 on 05 January 2026.