Climate, Pollution, and Maternal Health: Investigating the Impact of Temperature and Ozone on Birth Outcomes in Phoenix, Arizona

Human actions have significantly modified the global environment, leading to adverse effects on public health. Pregnant women, being particularly vulnerable, face increasing risks as climate change continues to raise concerns about its influence on maternal and birth outcomes. As climate change persists, exploration of its effects on maternal birth outcomes is of increasing importance. This study investigates two particularly salient factors (temperature and ozone pollution) and their impact on birth outcomes in Phoenix, Arizona. With its unique mountainous terrain, semi-arid climate, and high temperatures, Phoenix creates conditions that expose residents to elevated levels of pollutants and extreme heat. This paper uses a retrospective cohort study of pregnant mothers who delivered during October 2018–December 2020 at St. Joseph’s Hospital and monthly temperature data during the last trimester of each patient’s pregnancy. These data were gathered from the National Weather Service and Ozone Air Quality Index data from the Arizona Department of Environmental Quality. Our analyses revealed that the highest levels of ozone and elevated temperature exposure were both independently associated with lower birth weights. Furthermore, we found that ozone mediated the effect of temperature on birth weight outcomes (controlling for participants’ sociodemographics), demonstrating that the relationship between temperature and birth weight was explained through increases in ozone pollution.