Socioeconomic disparities in urban exposome in pregnant women in Yazd Birth Cohort study

Urban exposome during pregnancy have a significant impact on both maternal and child health, and socioeconomic status (SES) can further exacerbate these disparities. We conducted an analysis of data from 2,902 pregnant women within the Yazd Birth Cohort, a subset of the PERSIAN Birth Cohort. The different component of urban exposome including light at night (LAN), access to greenspaces, perceived environmental noise exposure, PM 2.5 , and meteorological factors were quantified at residential addresses. Reported household income (main analyses), education, employment status, and type of urban texture were use as SES indicators. We calculated absolute differences, relative ratios, and Gini coefficients of urban exposome components, and used multivariable linear regression to assess the association between SES indicators levels and exposures. We also reported interaction terms to determine the compounded disadvantage. Income-related differences were observed across several environmental exposures. High-income women had the highest mean LAN exposure, with a significant overall difference across income groups ( p = 0.041); however, in multivariable analysis, the association between middle income and LAN was borderline and not statistically significant (β = -1.105, p = 0.053). Low-income women had lower residential greenness than high-income women (β = -0.004, p = 0.017). Middle-income women had higher perceived environmental noise exposure than high-income women (β = 0.517, p = 0.034), although this association did not remain statistically significant after Bonferroni correction. No significant associations were observed for PM 2.5 or temperature measures. The Gini coefficient indicated the greatest inequality for perceived environmental noise exposure (0.59), followed by greenspace (0.20) and LAN (0.13). These findings suggest socioeconomic patterning of prenatal environmental exposures and underscore the importance of considering socioeconomic inequalities when addressing urban exposome during pregnancy.