Effects of Gestational Exposure to Extreme Heat and Heat Vulnerability on Early Life Blood Pressure Trajectories - PROJECT SUMMARY/ABSTRACT With rising temperatures, exposure to ambient extreme heat presents a current and future threat to public health. Research has demonstrated that heat exposure is associated with increased morbidity and mortality, both in causing conditions such as heat exhaustion, heat cramps, and heat stroke and in exacerbating existing conditions including those related to the respiratory, cerebral, and cardiovascular systems. There is little research, however, on the relationship between heat stress exposure and cardiovascular health (CVH), especially among children. Further, research has not investigated how the vulnerability of neighborhood built and social environments to ambient heat may attenuate such a relationship. This study will address the gaps present in the literature by examining how extreme heat exposure is associated with blood pressure, a key indicator of CVH, during early childhood. It will also explore how neighborhood heat vulnerability acts as both an exposure impacting CVH and a modifier on the pathway between heat exposure and CVH. To do so, this study will leverage data from a regional birth cohort with follow-up through early childhood which will be linked to validated, national data for ambient, built, and social environmental exposures. In Aim 1, I will describe trends of extreme heat events throughout the study period and how gestational extreme heat event (EHE) exposure and neighborhood vulnerability are impacted by socioeconomic and racial and ethnic disparities. In Aim 2, I will investigate associations between gestational EHE and blood pressure outcomes throughout early childhood. Finally, in Aim 3, I will investigate the role of gestational heat vulnerability with EHE and blood pressure. This study will advance our understanding of the mechanisms by which environment can affect CVH. This will inform future interventions and policy to reduce CVH morbidity from a growing public health threat during a sensitive period of life when prevention may be most effective.