Abstract Wildfires are a dire and imminent threat to human health. Wildfires are increasing in intensity, duration, and frequency. They are moving beyond wildland borders and into highly populated areas, which means more people are affected. It also means that particulate matter (PM) from wildfire smoke is combined with other pollutants from urban areas and intensifying poor air quality. The mother-fetal dyad is particularly susceptible to toxicants and ambient outdoor air pollution. Evidence has demonstrated that fine PM crosses the blood- placenta barrier and into fetal circulation. To address the critical scientific need for further research of in utero wildfire smoke exposure, we aim to: 1): Analyze the relationship between in utero wildfire smoke exposure and birth outcomes. Hypothesis 1a: There will be a decrease in gestational age at birth after in utero exposure to wildfire smoke. Hypothesis 1b: There will be a decrease in birth weight after in utero exposure to wildfire smoke; 2). Examine the relationship between in utero wildfire smoke exposure and physiological stability and clinical presentation at birth. Hypothesis 2a: There will be a difference in neonatal Apgar scores at 1 minute of life after in utero wildfire smoke exposure. Hypothesis 2b. There will be a difference in Apgar scores at 5 minutes of life after in utero wildfire smoke exposure. 3). Examine the relationship between in utero wildfire smoke exposure and requirements of neonatal intensive care at birth. Hypothesis: There will be an increase in NICU admissions at birth after in utero wildfire smoke exposure. This is a secondary analysis of data available from three sources used to conduct a population-based retrospective cohort study in Washington State. The three data sources include: 1. Air quality data from the Washington State University Laboratory for Atmospheric Research, 2. a Geographic Information System (GIS) that overlays coordinates for longitude and latitude of physical addresses with the air quality data and other spatial characteristics of neighborhoods where mothers resided and 3. maternal health and neonatal birth outcomes data available from the Washington State Department of Health. During the time period of interest (2010 to 2016) there were 611,182 births to mothers with a physical address in WA. For each of the three aims, a generalized linear mixed modeling (GLMM) framework will be used to examine the association between poor birth outcomes and exposure to PM2.5 while controlling for potential confounding variables. A multidisciplinary team with expertise in nursing, air quality, spatial analysis, and biostatistics will support this work. Conducting this research will build on my experience as neonatal intensive care nurse and support a strong foundation in my career as a nurse scientist with a focus on environmental exposure in the maternal child population. This study will build the science to better understand maternal and neonatal outcomes in re...