Mercury exposure of late pregnancy contributes to early childhood intelligence at 60 months

Abstract

Introduction: Many of the studies showed that prenatal mercury exposure have been adversely associated with early childhood intelligence. This study was designed to investigate the relationship whether prenatal mercury exposure at late pregnancy affects their 60 month old children’s intelligence by Mothers and Children’s environmental health (MOCEH) cohort study in Korea. Methods: A multi-center birth cohort project in Korea that began in 2006. We collected the 1202 mother’s blood sample from third trimester pregnant woman and compared the relative contribution of prenatal blood mercury (Hg) to 60 month old children’s intelligence. Mercury level was analyzed by AAS (atomic absorption spectrometry). In sub study(n=518) of this cohort, children of mothers were evaluated their intelligence using the Korean version of the Wechsler Preschool and Primary Scale of Intelligence, revised edition (WPPSI-R) at 60 months of age. Results: The arithmetic mean of log-transformed mercury blood concentration of late pregnancy and the total IQ of 60 month old children were 0.514mg/dL (10th percentile = 1.168; 90th percentile = 0.761; range = -1.456–1.167) and 103.5. In the Linear regression analysis, it showed negative association between prenatal log mercury level and performance (p=0.025), verbal (p=0.022), and total IQ scores (p=0.010) of children after controlling for maternal age, education, income, geographical region, status of breastfeeding, and gender of baby. Conclusions: In conclusion, mercury exposure during late pregnancy is associated with significant reduction in IQ scores at 60 month old children. Pregnant woman should be aware of mercury exposure during their pregnancy to prevent adverse effect of children’s intelligence.