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REFILE: Prenatal smoking tied to worse asthma in kids

[In para 8, changes "50%" to "50% higher" in story posted May 11, 2012 as 20120511epid009. Also adds "Dr." to name of researcher, throughout.]

NEW YORK (Reuters Health) – Children whose mothers smoked during pregnancy may have a tougher time controlling their asthma, a new study suggests.

The findings, from a study of nearly 2,500 U.S. kids, offers more motivation for doctors to ask moms and expectant moms about smoking, said lead researcher Dr. Sam Oh, of the University of California San Francisco, in an interview.

“Pregnancy is a great opportunity for smoking cessation,” he said.

For their study, the researchers focused on 2,481 black and Hispanic kids between the ages of 8 and 17 who all had asthma and were mostly from low-income families.

In the U.S., poor, minority children are at particular risk of asthma. About 16% of low-income black children have asthma, whereas the national prevalence is 9%, according to the U.S. Centers for Disease Control and Prevention.

In this study, almost 19% of African-American moms smoked at some point during pregnancy, as did 5.5% of Hispanic moms.

Overall, their kids were at greater risk of poor asthma control later in life, even when childhood secondhand-smoke exposure was taken into account — as well as other factors like a child’s age and asthma medication use.

About 30% of Hispanic kids and 38% of black kids had poorly controlled asthma symptoms — and the risk was 50% higher for those exposed to smoking in utero, vs unexposed kids.

“There are measurable effects even years down the road,” Dr. Oh said.

The findings do not, however, prove that prenatal smoking, itself, causes more-severe asthma symptoms later in life. They can only point to a correlation. But there is lab research, in animals and human cells, suggesting there could be a direct effect, Dr. Oh pointed out.

Fetal exposure to tobacco smoke may, for example, impair early lung development, or have lasting effects on the activity of certain genes.

The bottom line, according to Dr. Oh, is that there is already a host of reasons for pregnant women to quit smoking for good, and this may be one more.

“This study provides more impetus for healthcare providers to ask about smoking at each visit,” he said.

Some pregnant women may be able to quit with behavioral counseling. In nicotine replacement therapy or other medication can be used.

The study was published online April 20th in the Journal of Allergy and Clinical Immunology

SOURCE: http://bit.ly/IYU0T2

J Allergy Clin Immunol 2012.