Impact of dietary mercury intake during pregnancy on the health of neonates and children: a systematic review

Context: Growing evidence suggests that prenatal exposure to methyl mercury through the maternal diet could have great influence on the neurological and physical development of neonates and young children. Objective: The aim of this review was to evaluate the clinical repercussions of maternal exposure to methyl mercury during pregnancy on the health of fetuses, neonates, and children up to 8 years of age. Data Sources: The Web of Science, PubMed, CINAHL, Scopus, and Dialnet Plus databases were searched for articles published in English or Spanish from 1990 to 2020. Study Selection: Original articles published in English or Spanish from 1990 to 2020 were eligible for inclusion. All study designs were eligible. Animal studies were excluded. Two authors independently screened studies for inclusion. From the 971 records initially identified, 19 studies were included in the systematic review. Data Extraction: PRISMA guidelines were followed. Outcomes extracted included maternal dietary exposure to methyl mercury during pregnancy, possible health repercussions in offspring up to 8 years of age, and quantitative measurement of mercury in a biological sample. All studies met the requirements established for assessing both study quality and risk of bias. Results: Prenatal exposure to mercury was consistently associated with lower birth weight, but only one study reported a negative association with length at birth. Higher mercury levels were also related to lower scores in various neuropsychological and developmental tests. Conclusion: The literature shows clear evidence of the adverse effects of maternal methyl mercury exposure on anthropometric variables and cognitive or physical development in children. It is noteworthy, however, that mercury toxicity may sometimes be mitigated by other essential nutrients in the maternal diet, such as polyunsaturated fatty acids.