LAUSR

Associations of pesticide exposures during pre-conception with stillbirth have not been well explored. We linked Arizona pesticide use records with birth certificates from 2006-2020 and estimated associations of living within 500meters of any pyrethroid, organophosphate (OP), or carbamate pesticide applications during a 90 day pre-conception window or the first trimester, with stillbirth. We considered a binary measure of exposure (any exposure), as well as log-pounds and log-acres applied within 500m, in a negative control exposure framework with log-binomial regression. We included 1,237,750 births, 2,290 stillbirths, and 27 pesticides. During pre-conception, any exposure to pesticides were associated with stillbirth, including cyfluthrin (RR=1.97, 95% CI 1.17,3.32), zeta-cypermethrin (RR=1.81, 95%CI 1.20, 2.74), organophosphates as a class (RR=1.60, 95%CI 1.16, 2.19), malathion (RR=2.02, 95%CI 1.26, 3.24), carbaryl (RR=6.39, 95%CI 2.07, 19.74), and propamocarb hydrochloride (RR=7.72, 95%CI 1.10, 54.20) . During the first trimester, fenpropathrin (RR=4.36, 95%CI 1.09, 17.50), permethrin (RR=1.57, 95%CI 1.02, 2.42), organophosphates as a class (RR=1.50, 95%CI 1.11, 2.01), acephate (RR=2.31, 95%CI 1.22, 4.40), and formetanate hydrochloride (RR=7.22, 95%CI 1.03, 50.58) were associated with stillbirth. Interpretations were consistent when using continuous measures of pounds or acres of exposure. Pesticide exposures during pre-conception and first trimester may be associated with stillbirth.