The allowable level of lead in maternal blood may be too high to protect the fetus from brain damage and loss of intellect. A study appearing in the June, 2004 issue of Environmental Health Perspectives indicates that maternal blood containing less than the allowed level of 10 mcg/dl was enough to negatively impact the intelligence of the child. The study looked at the lead levels of the mother during pregnancy and at the child’s intelligence at age 10.
Lead levels in the mothers’ blood were measured at weeks 12, 20, 28, 36 and at birth. The level of lead in the children’s blood was tested twice yearly until the age of five and tested yearly between the ages of six and 10. The children’s IQ was tested yearly between the ages of six and 10.
High maternal blood lead during the third trimester of pregnancy was linked to lower IQ scores in children between the ages of six and 10. A lot of the brain’s development occurs in the third trimester of pregnancy. The reduction in IQ is dose dependent—the higher the lead levels, the lower the IQ. Half of the decline in IQ occurred with the mother having a few micrograms of lead in her blood. Damage was caused well below the allowable 10 mcg/dl allowed by the government.