Updated project metadata. Prenatal exposure to toxic metals is associated with altered placental function and adverse health outcomes. The underlying mechanisms linking in utero toxic metal exposures with later-in-life health remain unclear, though placental inflammation is posited as a potential driver. The aim of this study was to evaluate whether in utero metals presence is associated with sex-specific changes in placental protein expression. We hypothesized that sex-specific patterns of metal-associated placental protein expression would be observed, and metals presence would be positively associated with the altered expression of inflammation-associated pathways Using samples banked from the Extremely Low Gestational Age Newborn Study (ELGAN), umbilical cord tissue samples were analyzed via ICP-MS/MS for trace elements, and placental samples underwent a global untargeted proteomics analysis via LC-MS/MS. This work highlights the linkage between prenatal metals exposure and an altered placental proteome, revealing that metals in cord tissue were associated with largely distinct differences in placental protein expression, in a sexually-dimorphic manner.