As the climate continues to change, there is a heightened public health concern about how extreme weather events can affect adverse health outcomes, especially in more vulnerable populations. Children and pregnant women living in low-to-middle-income countries (LMICs) are considered highly vulnerable populations. Acute respiratory infections have become the number one cause of under-five mortality across the globe. Additionally, preterm birth, complications from preterm birth, and stillbirths are the number one cause of neonatal deaths worldwide. These adverse health outcomes are preventable. Thus, research needs to focus on preventable environmental determinants that can help reduce the number of childhood respiratory infections and adverse birth outcomes in LMICs. Air pollution and extreme heat are preventable risk factors because exposure levels can be determined by individual behaviors and population-level policies and action plans. Wildland fire smoke and dust storms can release substantial amounts of particulate matter into the atmosphere. Prior evidence has tied these extreme weather events with adverse respiratory and cardiovascular outcomes and premature mortality in children. Additionally, exposure to extreme heat has been linked to higher risks of preterm birth and stillbirth in high-income countries. The proposed biological mechanisms of how particulate matter and extreme heat can cause these outcomes involve oxidative stress and inflammation. Previous evidence has mainly come from high-income countries, which may be because of challenges in exposure measurement. The first chapter of this dissertation reviews the epidemiological evidence regarding the relationship of three extreme weather events (wildland fire smoke, dust, and extreme heat) and childhood respiratory outcomes and adverse birth outcomes in LMICs. The second chapter of this dissertation examines acute exposure to wildland and agricultural fire smoke affecting the risk of childhood respiratory outcomes in 14 LMICs. The third chapter is a case-study of acute exposure to heightened dust days and the risk of childhood cough in Benin. The fourth chapter studies the relationship between extreme heat and aims to identify specific susceptible windows of increased risk of preterm birth and stillbirth in a comprehensive set of LMICs. The latter three chapters expand on the limited evidence base of these exposure and outcome relationships in LMICs. The final chapter summarizes key findings, describes the implications and innovations of this research, and highlights future research objectives to build upon this dissertation research.