Heat-4P will provide comprehensive knowledge on physiological and social factors increasing vulnerability to the adverse health effects of heat during pregnancy for women and children and new understanding on the biological cascade of events leading to these health effects. We will capitalize on the wealth of individual data on pregnant women and children from 4 longitudinal cohorts and new measure of health biomarkers during pregnancy. We will combine cutting-edge temperature exposure data and advanced methods to capture the chronic and acute effects of heat, and more generally extreme temperatures, and will explore long-term effects of heat on children neurodevelopment. We will disseminate findings through networks of maternal health professionals, population and decision-makers. Heat-4P brings together an unprecedented interdisciplinary team (epidemiologists, physiologists, obstetricians, pharmacologists, biologists, public health professionals) to gain understanding of how heat affects maternal and child health and its social inequalities. Evidence to better identify territories and sub-populations with a higher risk, critical periods of exposure, and risk factors will support effective public health strategies.