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Parents' Smoking Gives Children Asthma, Wheezing

WebMD Health News

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 wheezing.

"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 WebMD.

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.

Vital Information:

  • 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 increases risk.
  • 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.

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