Background: The adverse health influences of polycyclic aromatic hydrocarbons (PAHs) exposures have been examined in several previous research. However, the evidence on the health influences of PAHs exposure during pregnancy and childhood is scarce, with no study on the infant's liver function. Therefore, in this study, the association of in-utero exposure to particulate matter-bound PAHs (PM-bound PAHs) on the umbilical liver enzymes was investigated. Methods: A total of 450 mother-pair samples were assessed in this cross-sectional study in Sabzevar, Iran (2019–2021). The concentrations of PM-bound PAHs were estimated based on spatiotemporal models at residential addresses. The umbilical cord blood alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT) were measured as indicators of infant's liver function. The association of PM-bound PAHs with umbilical liver enzymes was evaluated using multiple linear regression, controlled for relevant covariates. The quantile g-computation (g-comp) was used to investigate the combined impact of the 15 PAHs on liver function biomarkers. Results: Higher levels of total 4-ring PAHs, Dibenzo[a,h]anthrancene, Anthracene, Pyrene, Benzo[a]anthracene, Phenanthrene, Fluorene, Acenaphthylene and Naphthalene were associated with higher umbilical ALP. An increase in total 5-ring PAHs, Benzo[g,h,i]perylene, Benzo[a]pyrene and Chrysene was associated with higher umbilical AST levels. Each 1 ng/m3 increase in exposure to Benzo[g,h,i]perylene was related with 182.21 U/L (95 % CI: 116.11, 248.31, P < 0.01) increase in umbilical GGT. PAHs mixture exposure was positively associated with higher umbilical AST and ALT, while no significant associations were noted for ALP and GGT. We observed a potentially stronger association for girls compared to boys based on umbilical ALT and AST. However, for GGT and ALP, these associations were stronger for boys compared to girls. Conclusion: Overall our findings suggested that exposure to PAHs during pregnancy had adverse effects on infant's liver function.
