Association between maternal PAH exposure and immune-inflammatory indices during pregnancy

Polycyclic aromatic hydrocarbons (PAHs) are endocrine-disrupting chemicals, yet the relationship between maternal PAH exposure during pregnancy and maternal immune-inflammatory indices remains poorly understood. Therefore, we included 2581 pregnant women in the Zunyi birth cohort and measured their concentrations of PAH metabolites during pregnancy and collected pregnancy related immune examination indicators to explore the association between PAH metabolites in pregnancy urine and maternal immune inflammation indicators.

Generalized linear regression models were used to assess correlations between PAH metabolites and immune-inflammatory indices. Restricted cubic spline (RCS) models were employed to characterize dose-response relationships. Bayesian kernel machine regression (BKMR) models evaluated overall effects and non-linear associations of PAH metabolites with these indices. Weighted quantile sum (WQS) regression quantified the relative contribution of individual PAH metabolites to immune-inflammatory alterations.

Our results showed that 1-Hydroxynaphthalene (1-OHNAP), 2-hydroxynaphthalene (2-OHNAP), 2-hydroxyfluorene (2-OHFLU), and 9-hydroxyphenanthrene (9-OHPH) are negatively correlated with white blood cell (WBC) count, positively correlated with systemic immune inflammation index (SII), negatively correlated with systemic inflammatory aggregation index (AISI), negatively correlated with neutrophil to lymphocyte ratio (NLR), and positively correlated with platelet to lymphocyte ratio (MLR). Additionally, RCS models identified dose-response relationships between 1-OHNAP, 2-OHNAP, 1-hydroxypyrene (1-OHPYR), 9-OHPH, 2-hydroxyphenanthrene (2-OHPH), and 4-hydroxyphenanthrene (4-OHPH) and the aforementioned indices (excluding PLR). Furthermore, BKMR models demonstrated that PAH metabolites were negatively associated with WBC count and NLR; at low combined concentrations, they were negatively associated with MLR and positively associated with PLR, with no such associations observed for SII or AISI. WQS regression identified 9-hydroxyfluorene (9-OHFLU), 9-OHPH, 4-OHPH, 2-OHPH, and 1-hydroxyphenanthrene (1-OHPH) as key metabolites driving these associations.

Collectively, our findings demonstrate that maternal exposure to PAH metabolites during pregnancy is associated with maternal immune-inflammatory indices. Limiting PAH exposure during gestation may help protect maternal and fetal health.