The study at the University of Michigan shows that women who take 1,200 milligrams of calcium daily have up to a 31 percent reduction in lead levels.
Women who used lead-glazed ceramics and those with high bone lead levels showed the largest reductions; the average reduction was about 11 percent, said Howard Hu, chair of the Department of Environmental Health Sciences at the School of Public Health.
The study is available online in Environmental Health Perspectives, the official journal of the U.S. National Institute for Environmental Health Sciences.
Hu, who is also affiliated with the University of Michigan School of Medicine, said this is the first known randomized study examining calcium supplementation on lead levels in pregnant women.
"We and others have previously shown that during pregnancy, mothers can transfer lead from their bones to their unborn -- with significant adverse consequences--making maternal bone lead stores a threat even if current environmental lead exposures are low," Hu said.
"This study demonstrates that dietary calcium supplementation during
pregnancy may constitute a low-cost and low-risk approach for reducing this threat," the researcher added.
Lead exposure is a great concern for pregnant and lactating women, especially in developing countries where lead exposures have been high until recently, and for women with occupational exposure.
The study showed that reductions in blood lead levels were more evident in the second trimester at 14 percent than in the third trimester at 8 percent.
The most compliant group of women in the study (those who consumed greater than 75 percent of the assigned 1,200 milligram doses of calcium per day) showed a 24 percent decrease.
omen in the most compliant group who also reported using lead glazed ceramics and had the highest bone lead levels saw the greatest reduction of 31 percent.
Researchers analyzed 557 women recruited from the Mexican Social Security Institute prenatal clinics, which treat the low to moderate income population of Mexico City.
ll were in their first trimester; roughly half were assigned calcium and half a placebo.