Early Cord Clamping Boosts Lead in At-Risk Infants
Tue Dec 11, 2007 6:52 pm (PST)
http://www.medscape .com/viewarticle /566984
Early Cord Clamping Boosts Lead in At-Risk Infants
By David Douglas
NEW YORK (Reuters Health) Dec 05 - In settings where lead exposure is
high,
the practice of immediate umbilical cord clamping after delivery can
give
rise to elevated blood lead levels in infancy, in part by decreasing
iron
status, according to US and Mexican researchers.
"Clamping the umbilical cord in the first 10 to 15 seconds after birth,"
lead investigator Dr. Camila M. Chaparro told Reuters Health, "is
frequently
practiced in many delivery settings -- both in the developed and
developing
world -- and is a practice that was instituted with little scientific
evidence justifying it."
In the November issue of the Journal of Pediatrics, Dr. Chaparro of the
Pan
American Health Organization, Washington, DC and colleagues note that in
Mexico City, lead exposure is high and iron deficiency is also common.
To investigate whether infant iron status, modified by umbilical cord
clamping time and infant feeding mode, affected infant blood lead
concentration, the researchers randomized 266 prospective mothers in
Mexico
City to 10-second or 2-minute umbilical cord clamping at the time of
delivery.
Examination of data on maternal lead exposure at baseline and on infant
feeding showed that maternal blood lead concentration, infant ferritin,
and
breast-feeding practices predicted infant blood lead concentration at 6
months.
In infants with higher placental blood lead concentration and breast-fed
infants not receiving any iron-fortified formula or milk at 6 months,
say
the researchers, "early clamping increased infant blood lead
concentration. "
The researchers suggest that the most plausible underlying mechanism is
upregulation of divalent metal transporter 1 in response to lowered iron
status, resulting in greater uptake of lead. Nevertheless, they point
out
that for a variety of reasons, only 23% of the total effect on infant
lead
status could be attributed to changes in iron status.
"Clamping the cord immediately not only decreases infant iron levels,"
concluded Dr. Chaparro, "but may increase infant blood lead levels. Both
iron deficiency and elevated blood lead levels are independently and
negatively associated with infant mental development, and waiting a few
minutes to clamp the cord at birth is one way to prevent the development
of
these conditions."
J Pediatr 2007;151:506- 512.
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