Maternal Blood Mercury Concentration and Infant Weight

Birth weight is a strong determinant of attained weight at early ages. Until now, many studies have reported that low birth weight corresponds with high mercury levels. However, the relationship between mercury exposure and attained weight of infant has not been well studied.

Therefore, the aim of a recent study was to assess the degree of prenatal exposure to mercury by measuring the total mercury levels in maternal and cord blood, and examine the relationship between the mercury level during pregnancy and the attained weight of infant during the first 24 months of life.

The prospective cohort study of Mothers and Children's Environmental Health (MOCEH) was built up in 2006, and 921 mother–infant pairs were recruited. Information on the socio-demographic characteristics, health behavior and environmental exposure were collected from an interview with trained nurses.

After delivery, infants and mothers were followed up at 6, 12 and 24 months and the weights of the infants were measured.

The mercury concentrations in the late maternal blood (β=−0.19. p=0.05) and cord blood (β=−0.36. p=0.01) were negatively associated with the infants' attained weight over the first 24 months of age.

The infants' attained weight in the small for their gestational age (SGA) group was lower than the normal birth weight group at the highest quartile of the mercury level.

Therefore, efforts should be made to reduce the mercury level in the maternal blood at late pregnancy and cord blood.

Further research on the possible harmful effects of prenatal mercury exposure on postnatal growth is recommended.

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