Smoking in pregnancy harms baby immunity
(Reuters)
Updated: 2006-09-28 10:35 LONDON - Smoking during pregnancy can affect the
baby's immune system which may explain why asthma and respiratory problems are
more common in children whose mothers smoke, Australian scientists said in a
study on Thursday.
Babies of smokers are more likely to suffer from respiratory infections than
children of non-smokers but until now it has not been clear why.
The scientists said it may be due to changes to biological receptors in the
baby's immune system that are responsible for recognising and fighting
infections and bacteria.
"This is the first prospective study to examine the effect of smoking during
pregnancy in terms of these aspects of newborn innate immune function," said
Paul Noakes of the University of Western Australia in Perth.
The researchers, who reported the findings in the European Respiratory
Journal, compared 60 newborn babies whose mothers had smoked during pregnancy
and 62 other infants born to non-smokers or women who had quit.
They measured the expression of several signalling compounds in the immune
system linked to specific cell receptors known as TLRs in the infants.
In the babies of mothers who smoked, they discovered impaired production of
two compounds, interleukin-6 and tumour necrosis factor-alpha (TNF-a).
"We were focusing on the innate, or congenital, immune system. This provides
protection until the baby develops an acquired immune system, which becomes
increasingly powerful through contact with new antigens," said Susan Prescott,
who also worked on the study.
The researchers said the findings show that foetal exposure to cigarette
smoke is associated with changes that both weaken innate immune defences and
slow the development of the acquired immune system.
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