Associations between a metal mixture and infant negative affectivity: Effect modification by prenatal cortisol and infant sex

In-utero exposures interact in complex ways that influence neurodevelopment. Animal research demonstrates that fetal sex moderates the impact of joint exposure to metals and prenatal stress measures, including cortisol, on offspring socioemotional outcomes. Further research is needed in humans. We evaluated the joint association of prenatal exposures to a metal mixture and cortisol with infant negative affectivity, considering sex differences. Analyses included 226 (29% White, Non-Hispanic) mother-infant pairs with data on exposures and negative affectivity assessed using the Infant Behavior Questionnaire-Revised in 6-month-olds. Results showed that girls whose mothers had higher cortisol had significantly higher scores of Fear and Sadness with greater exposure to the mixture. Examining higher-order interactions may better elucidate the effects of prenatal exposure to metals and cortisol on socioemotional functioning.