Association between serum metal exposure in early pregnancy and preterm birth: Mediation by inflammatory blood cell parameters.

Several studies have linked metal exposure to preterm birth (PTB), but the underlying mechanisms remain poorly understood. This study investigated the mediating role of inflammatory blood cell counts in the relationship between metal exposure at 10-12 weeks of gestation and PTB. The combined effects of metals were assessed using quantile g-computation (Q-gcomp) and Bayesian kernel machine regression (BKMR) models. Linear and logistic regression models evaluated the associations between individual metal levels and blood cell counts, as well as their impact on PTB risk. Mediation analysis was conducted to explore the potential role of blood cell counts in mediating the metal exposure-PTB relationship. Metal exposure was significantly associated with PTB, with serum levels of barium (Ba), lead (Pb), and cadmium (Cd) showing positive correlations with PTB risk. Mediation analysis revealed that white blood cell (WBC) and neutrophilic granulocyte (NE) counts mediated the association between serum Ba exposure and PTB. Additionally, mixed-exposure analysis demonstrated that higher overall metal exposure was linked to an increased risk of PTB. This study highlights the association between early pregnancy serum Ba exposure and PTB, with WBC and NE counts mediating this relationship. These findings offer valuable insights into the mechanisms underlying PTB.