Children whose mothers smoked during pregnancy may have an increased risk of asthma - even if they were not exposed to secondhand smoke after birth, a large study of European children suggests.
Many studies have found that secondhand smoke may worsen kids' asthma symptoms, or possibly raise their risk of developing the lung disease in the first place. But it's been less clear if smoking during pregnancy is linked to asthma. Most studies have not been able to tease out the possible effects from those of secondhand smoke after birth.
The new study, however, had a large enough group of kids who were exposed to smoking in the womb, but not after birth, according to the researchers.
And it found that those children were two-thirds more likely to have asthma by age six, versus kids whose moms did not smoke during pregnancy. Even smoking during the first trimester alone was linked to higher asthma risk.
The findings cannot prove that prenatal smoking was the cause.
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