Parents' Smoking Gives Children Asthma, Wheezing
Dec. 2, 1999 (Atlanta) -- The largest study of its kind confirms earlier
reports: parents who smoke greatly increase their children's risk of asthma and
"There is no question that a parent who smokes -- especially a mother --
puts her child at risk of asthma," Norman H. Edelman, MD, tells WebMD in an
interview seeking objective commentary. Edelman serves as consultant for
scientific affairs to the American Lung Association.
The study collected data on almost 19,000 children aged 6 and 7 and on more
than 21,000 adolescents aged 13 and 14. Its findings show that in Italy --
where at least one parent smokes in more than half of all families -- a large
proportion of children and adolescents can lay the blame for their asthma and
wheezing directly on their parents' smoking.
"We estimated that 15% ... of the current asthma cases among children
and 11% ... of the current wheezing cases among adolescents are attributable to
parental smoking in Italy," say Nera Agabiti and colleagues with the
internationally regarded group of epidemiologists known as the SIDRIA
Collaborative Group. The group published their findings in the November issue
of the journal Epidemiology.
The link between parents who smoke and children with asthmatic disease is by
no means unique to Europe. They echo the results of a 1997 report by the
California Environmental Protection Agency (EPA), which estimated that parents
who smoke each year cause 8,000 to 26,000 new cases of childhood asthma in the
U.S. and make existing asthma worse in 20% of the 2 million to 5 million
children who already have the disease.
The percentage of actual asthma cases in the U.S. caused by parental smoking
is smaller than that seen in Italy only because a smaller percentage of U.S.
adults are smokers. "In the U.S., the attributable risk would be lower
because the prevalence of smoking is lower," Michael Lipsett, MD, lead
author of the respiratory disease section of the California EPA report, tells
But Lipsett, now affiliated with the University of California, San
Francisco, notes that the risk posed to children by even one household smoker
was the same in the large Italian study as it was in the analysis of numerous
smaller U.S. studies reported in the California EPA report.
The Italian study broke new ground in teasing out new information about
children's exposure to secondhand smoke. Although having a mother who smokes is
more dangerous to a child's respiratory health than having a father who smokes,
smoking by fathers remains a health threat to the child. The study also found
maternal smoking during pregnancy was a strong predictor of asthma or wheezing
in young children, but that this effect apparently diminished over time.
Smoking by the father during pregnancy had little if any effect on the
long-term respiratory health of children.
Agabiti et al. and colleagues also collected data on children whose parents
suffered from childhood asthma or wheezing. They found that parental smoking
appeared to be especially risky for these children "genetically
predisposed" to asthma and wheezing attacks.
- Parental smoking increases the risk of asthma in children and the risk of
wheezing in adolescents.
- Maternal smoking poses the greatest danger, but paternal smoking also
- Parental smoking appears to be a contributing factor in asthma and wheezing
attacks in high-risk children -- youths with a family history.
- Maternal smoking during pregnancy increases the risk of asthma and wheezing
in young children, but the effect appears to diminish over time.