Lead accumulates in bone. During pregnancy, physiologic changes occur prompting bone resorption in order to provide calcium to the growing fetal skeleton also release the lead stored in bone into a pregnant woman's circulation. We have previously demonstrated that lead stores mobilized into the circulation of pregnant women pose a major threat to fetal development. This is particularly unfortunate since bone lead stores, once accumulated, persist for decades, thereby jeopardizing the pregnancies of women even if their current lead exposures have subsided. What then can be done for the many thousands of women who have had lead exposure while growing up and who want to have healthy children? To address this question, in 2000, this project embarked on a randomized intervention trial to test whether a bedtime nutritional supplement of 1,000 mg of calcium can significantly reduce fetal lead exposure and toxicity by suppressing bone resorption in the pregnant mother.