Maternal early-pregnancy and newborn biomarkers of prenatal exposure to Hg, Mn, Se and Zn and child neurobehavioral development in the first 24 months: A prospective cohort study

BACKGROUND: There is limited information on the joint effect of multiple-metal(loid)s on infant development. OBJECTIVE: This study aimed to investigate the joint impact of maternal early pregnancy and newborn exposures to mercury (Hg), selenium (Se), manganese (Mn) and zinc (Zn) on early child neurodevelopment. METHODS: Included were 2771 mother-infant pairs from the Shanghai Birth Cohort who had maternal early pregnancy blood and newborn cord blood Hg, Mn, Se and Zn measured. Neurobehavior was assessed using the Ages and Stages Questionnaire (ASQ-3) instrument at age 6 months, and Bayley Scales of Infant & Toddler Development (BSID-III) at age 24 months. Linear regression was used to examine effect of metal(loid)s (in tertiles), and Bayesian kernel machine regression (BKMR) for exposures mixtures on child neurobehavior. RESULTS: The ASQ-3 communication score was 1.25 lower (95% CI: -2.11, -0.38) in the high tertile group of maternal Hg (> 2.09 μg/L), 1.36 lower (95% CI: -2.45, -0.246) in high cord blood Hg (> 2.64 μg/L), 1.61 lower ( 95% CI: -1.07, -0.15) in high maternal Mn, and 1.10 higher (95% CI: 0.04, 2.16) in high cord blood Se at age 6 months. High maternal Hg was also associated with 1.80 increased social-emotional (SE) scores (95%CI: 0.22, 3.37). At age 24 months, high maternal Zn (> 5.62 μg/L) was associated with 2.66 higher (95%CI 0.43, 4.89) cognition score. These associations were persistent with adjustment for the other metal(loid)s by using BKMR models. The overall effects of maternal blood and cord blood metal(loid) mixture were both adversely associated with communication score and SE at age 6 months, respectively. CONCLUSIONS: The early-pregnancy and newborn biomarkers of prenatal exposure to Hg show negative effect on early child development. The overall combined impact of maternal exposure to Hg, Mn, Se and Zn mixtures appear to be adverse in the first 24 months of life.