Association between maternal serum metals mixtures and adverse birth outcomes: A prospective cohort study

Maternal exposure to heavy metals is linked to adverse birth outcomes, but combined effects remain understudied. Examine associations between mid-pregnancy serum metals (Iron [Fe], Selenium [Se], Rubidium [Rb], Thallium [Tl], Antimony [Sb], and Iodine [I]) and preterm birth (PTB), congenital anomalies, low birth weight (LBW), macrosomia, SGA, and LGA. Prospective cohort (n = 429 mother-infant pairs). Serum metals quantified via ICP-MS. Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression assessed mixture effects. Both BKMR and WQS analyses indicated that combined metal exposure correlated positively with PTB risk, but inversely with congenital anomalies and LGA. Thallium (Tl) and iron (Fe) demonstrated negative associations with PTB (Tl exhibiting highest weight), whereas selenium (Se), antimony (Sb), and iodine (I) showed positive associations (Se as primary contributor). WQS regression confirmed: Positive association with PTB (β = 1.366, 95 % CI: 0.041-2.692; p = 0.043), Negative association with LGA (β = -2.224, 95 % CI: -3.783--0.666; p = 0.005). Our findings advance understanding of prenatal multi-metal exposure risks, revealing complex relationships between elemental mixtures and birth outcomes. This evidence supports targeted preventive strategies for maternal-fetal health protection.