Accumulation of Mixed Heavy Metals in Maternal Hair and Risk of Pre-Eclampsia: A Prospective Nested Case-Control Study.

Heavy metals (lead [Pb], cadmium [Cd], arsenic [As], mercury [Hg], manganese [Mn], copper [Cu], zinc [Zn], and iron [Fe]) might be risk factors for pre-eclampsia (PE), whereas their joint effect remains unclear. To address this issue, we conducted a nested case-control study consisting of 49 PE cases and 329 controls from a Chinese prospective birth cohort and divided the participants into low/high and quartile groups based on hair metal concentrations. We used logistic regression models and a weighted quantile sum (WQS) model to investigate the independent and mixed associations between these eight heavy metals in maternal hair and the risk of PE. After multivariable adjustment, high hair Pb was associated with a 2.53-fold increased risk of PE, and significantly higher risks of PE were also observed in quartiles 2 to 4 of Pb and quartiles 3 to 4 of Fe. The WQS model revealed a statistically significant association between maternal co-exposure to all eight heavy metals and the risk of PE, with Pb, As, and Fe presenting the biggest risk. Therefore, high maternal exposure to heavy metals may increase the risk of PE. It is crucial to consider co-exposure to multiple heavy metals throughout pregnancy in future research endeavors.