Prenatal wildfire smoke, first trimester proteome, and subsequent child behavioral outcomes: An exploratory study

California has the highest air pollution levels of any state in the United States, due in part to the high levels of drought and the prevalence of wildfires in the state. Given the increasing frequency and magnitude of wildfires globally, it is critical that we gain a better understanding of the risks posed by wildfire smoke, especially to susceptible populations. In particular, investigators have posited that fetal developmental processes are disrupted by inhalation of wildfire smoke by pregnant women. In this study, we obtained proteomic data by drawing blood from women in their first trimester of pregnancy. We then linked data estimating levels of particulate matter (PM_2.5) related to wildfire smoke at the census-tract level to participants' prenatal residential address. Finally, when their children were 3-5 years of age, mothers completed questionnaires assessing their children's behavior and temperament (N = 86). We found that in relation to exposure to wildfire smoke during the first trimester, the prenatal proteome was enriched in proteins involved in inflammation, neurodevelopment, and tissue development. This enrichment, in turn, predicted higher levels of mother-reported exuberant behavior and lower levels of fearfulness in the children. Thus, prenatal exposure to wildfire smoke may influence both immune and developmental processes in utero, with potential long-term effects on child behavior and temperament. Further research should focus on gaining a more comprehensive understanding of both the mechanisms underlying these associations and their implications for public health.