In pregnant women with low exposure to lead, high intakes of calcium (>2000 mg/day) decreased the serum concentration of lead, which could potentially minimize fetal exposure to lead. This is twice the amount of calcium recommended for women during pregnancy and approaches the Upper Level for calcium of 2500 mg/day. The mechanism by which high calcium intake blunts pregnancy-induced increases in maternal blood lead may involve decreased lead absorption in the intestine or decreased maternal bone resorption with subsequent release of lead. Either mechanism could decrease maternal blood concentrations of lead and potentially limit fetal accumulation of lead.