MedWire News: Asthma exacerbations are more frequent and severe in asthmatic pregnant women who smoke than in their nonsmoking counterparts, research shows.
"Smoking and severe asthma exacerbations in pregnancy are risk factors for low birth weight babies," explain Peter Gibson (John Hunter Hospital, Newcastle, Australia) and team in the journal Thorax.
But they add: "No studies have assessed the clinical implications of smoking on asthma exacerbations in pregnancy."
To address this, the researchers studied 80 pregnant women with asthma and 46 pregnant women without the condition (controls) who were aged 18-43 years. All the participants underwent comprehensive assessments at 18, 30, and 36 weeks gestation.
Participants with asthma also completed the Asthma Control Questionnaire (ACQ) at each visit, with a higher score indicating worse asthma control, and the number of exacerbations they experienced during pregnancy was also recorded.
The researchers found that women with asthma were more likely to be current smokers (35%) than those without the condition (15%).
In women with asthma, current (n=27) and former (n=27) smokers both experienced an average of 2.0 exacerbations during pregnancy compared with an average of 1.5 exacerbations among those who had never smoked (n=26).
ACQ scores were significantly higher during asthma exacerbations in women who were current smokers than in those who had never smoked, at a median of 2.17 versus 1.17.
Mean birth weights were also significantly lower among children born to smokers than in those born to women who had never smoked, at 3207 g versus 3479 g, in the asthma and control groups combined.
Gibson and team conclude: "Pregnant women with asthma who smoke have exacerbations which are more severe and more frequent than never smokers.
"Severe exacerbations during pregnancy are a significant risk factor for low birth weight, as is smoking itself.
They add: "Smoking cessation should be particularly encouraged in pregnant women with asthma, as the effects of asthma on poor perinatal outcomes may be greater among smokers than nonsmokers."
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