2.2.5.0 for windows

Variables were rst examined for outliers and skewness. Samples greater than 3SD from the mean (N = 7)
were removed. Pearson correlations and independent samples t-tests were employed to explore the potential effect of sociodemographic and health-related variables on infant methylation levels. All variables found to be signi cantly associated with the outcomes examined were included as covariates in subsequent analyses. Separate hierarchical regression analyses were performed to evaluate the independent and interactive effects of maternal PRS and exposure to air pollution on infant methylation levels. Covariates were entered in the rst step. Maternal PRS and exposure to air pollution were entered in a second step to assess their independent effect on infant's methylation levels, whereas their interactive effect was included in a third step. Maternal PRS and exposure to air pollution were centered at the sample means, infant's sex was centered at males. Signi cant interactions were examined with simple slope analyses. Supplementary exploratory analyses were performed to investigate possible timing effects related to the trimester of exposure to air pollution. Speci cally, as pollution levels at each trimester were moderately correlated, separate models for each trimester were conducted. All the analyses were performed using Jamovi 2.2.5.0 for Windows (The Jamovi Project, 2021).