Contact: Laura Bailey
University of Michigan
Calcium during pregnancy reduces harmful blood lead levels
ANN ARBOR, Mich.---Pregnant women who
take high levels of daily calcium supplements show a marked reduction
in lead levels in their blood, suggesting calcium could play a critical
role in reducing fetal and infant exposure.
A new 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.
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.
Hu is the principal investigator of the study and one of the senior authors on the paper, which 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
"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."
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. Developing fetuses and nursing babies are
exposed to lead from either current exposures to mothers or from the
mobilization of maternal skeletal lead stores accumulated from prior
years of exposure. Bone lead can stay in the body for decades, so even
with minimal environmental exposure, the fetus or nursing infant can
still be at great risk from maternal stores of lead.
exposure during fetal development and infancy can cause low birth
weight or slow weight gain after birth, cognitive defects such as lower
intelligence scores, lower motor and visual skills, or even
miscarriage. Damage from lead exposure and poisoning is usually
"The bottom line is that obstetricians and
pediatricians should consider adding calcium supplementation to the
prenatal vitamins normally recommended in pregnant women, particularly
if their patients have a significant history of environmental or
occupational lead exposure," Hu said.
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. Women 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.
analyzed 557 women recruited from the Mexican Social Security Institute
prenatal clinics, which treat the low to moderate income population of
Mexico City. All were in their first trimester; roughly half were
assigned calcium and half a placebo.
This recent study
corresponds with a previous study performed by the same group of
investigators showing that 1,200-milligram daily calcium
supplementation during lactation reduced maternal blood lead by 15-20
percent, and breast milk lead by 5-10 percent. This is the first
randomized trial to evaluate the effect of supplementation during
pregnancy, when lead is more easily transferred to the fetus, Hu said.
and affiliations include: Adrienne S. Ettinger, Harvard School of
Public Health and U-M SPH; Héctor Lamadrid-Figueroa, Martha M.
Téllez-Rojo, and Adriana Mercado- García, Mexican National Institute of
Public Health; Karen E. Peterson, Harvard SPH and U-M SPH; Joel
Schwartz, Harvard SPH; Mauricio Hernández-Avila, Mexican National
Institute of Public Health and Mexican Ministry of Health
The study is available at:
For more on Hu, visit: http://www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1188
For more on the Department of Environmental Health Sciences at U-M SPH, see:
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