UCSF

Preterm birth, defined as birth prior to 37 weeks of gestation, affects approximately 1 in 10 live births and is the leading cause of neonatal morbidity and mortality in the United States. One known risk factor associated with preterm delivery is perinatal exposure to air pollution, and more specifically, fine particulate matter (particulate matter <2.5μm in diameter (PM2.5)).

In this dissertation, I present three retrospective cohort studies investigating the relationship between PM2.5 and preterm birth. The full cohort consisted of all births in the state of California, from 2007 to 2020. Data included maternal sociodemographic characteristics, residential address at the time of delivery, hospital delivery records, and infant characteristics. I combined this cohort data with publicly available data sources, including census data, transportation data, and environmental data repositories.

In the first study (Chapter 2), I examined the role that exposure to major highways plays in preterm birth risk. Comparing the risk associated with residential distance to major roads to that of fine particulate matter exposure, I found that the latter was significantly associated with preterm birth, while the former was not.

In the second (Chapter 3), I considered the impacts of wildfire-driven high PM2.5 values. This study focused specifically on the San Francisco Bay Area during the 2018 California Camp Fire. Both exposure to the wildfire smoke and the degree of wildfire smoke experienced were significantly associated with preterm birth.

Finally, in the third study (Chapter 4), I investigated whether a positive test for SARS-CoV- 2 modified the association between PM2.5 and preterm birth. I found that such an effect modification was not present.