The available literature indicates a linear relationship with mercury levels and IQ deficit. - GreenMedInfo Summary

Mercury exposure in pregnancy has been associated with both pregnancy complications and developmental problems in infants. Apart from industrial accidents and contaminated food, mercury exposure is likely to arise from predatory fish consumption, environmental contamination and dental amalgam restorations placed before or during pregnancy. It would be prudent to recommend that pregnant women avoid these potential problems and minimize any risk. The available literature indicates a linear relationship with mercury levels and IQ deficit, and therefore a safe limit of mercury cannot be calculated.