Interaction of prenatal maternal selenium and manganese levels on child neurodevelopmental trajectories-the Shanghai birth cohort study

Objective: The fetal brain is particularly plastic, and may be concurrently affected by chemical exposure and malnutritional factors. Selenium is essential for the developing brain, and excess manganese exposure may exert neurotoxic effects. However, few epidemiological studies have evaluated the interaction of manganese and selenium assessed in different prenatal stages on postnatal neurodevelopmental trajectories. Methods: This study contained 1024 mother-child pairs in the Shanghai-birth-cohort study from 2013 to 2016 recruited since early/before pregnancy with complete data on manganese and selenium levels in different prenatal stages and infant neurodevelopmental trajectories. Whole blood manganese and selenium in early pregnancy and around birth were measured by inductively-coupled-plasma-mass-spectrometry (ICP-MS), children's cognitive development was evaluated at 6, 12, and 24 months of age using Age & Stage-Questionnaire (ASQ)-3 and Bayley-III. Multiple linear regression was used to investigate the interaction of prenatal selenium and manganese on neurodevelopmental trajectories. Results: The prenatal manganese and selenium levels were 1.82 +/- 0.98 mu g/dL and 13.53 +/- 2.70 mu g/dL for maternal blood in early pregnancy, and 5.06 +/- 1.67 mu g/dL and 11.81 +/- 3.35 mu g/dL for umbilical cord blood, respectively. Higher prenatal Se levels were associated with better neurocognitive performances or the consistently-high-level trajectory (P < 0.05), with more significant associations observed in early pregnancy than around birth. However, such positive relationships became non-significant or even adverse in high (vs. low) manganese status, and the effect differences between low and high manganese were more significant in early pregnancy. Conclusions: Prenatal Selenium was positively associated with child neurodevelopment, but prenatal high manganese may mitigate such favorable effects. The effects were mainly observed in earlier prenatal stage.