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Published on: August 7, 2017
Maternal second-hand smoke exposure in pregnancy is associated with childhood asthma development
Elinor Simons1, Teresa To2, Rahim Moineddin3
1Clinical Epidemiology and Health Services Research, University of Toronto, Ontario, Canada; Child Health Evaluative Sciences, Hospital for Sick Children, Toronto, Ontario, Canada.
Insights
Maternal exposure to second-hand smoke during pregnancy increases the risk of childhood asthma. This risk persists even for children of non-smoking mothers exposed to environmental tobacco smoke.
Area of Science:
- Environmental Health
- Pediatrics
- Epidemiology
Background:
- Childhood asthma is a significant public health concern.
- Maternal active smoking during pregnancy is a known risk factor for childhood asthma.
- The impact of maternal second-hand smoke exposure during pregnancy on asthma development requires further investigation.
Purpose of the Study:
- To investigate the longitudinal associations between maternal smoke exposure during pregnancy and the development of childhood asthma.
- To evaluate the independent effect of maternal second-hand smoke exposure on asthma incidence.
Main Methods:
- A population-based cohort study of 5619 seven-year-old children in Toronto.
- Data collected on physician-diagnosed asthma, maternal smoking, home second-hand smoke exposure, and family history.
- Cox proportional and discrete-time hazard survival analyses were employed.
Main Results:
- 15.5% of children developed asthma.
- Maternal smoking or second-hand smoke exposure during pregnancy was associated with a higher likelihood of childhood asthma (adjusted HR 1.30).
- This association remained significant for non-smoking mothers exposed to second-hand smoke (adjusted HR 1.34) and children with recent asthma symptoms (adjusted HR 1.36).
Conclusions:
- Maternal exposure to second-hand smoke during pregnancy is linked to new cases of childhood asthma.
- Prevention strategies should address smoking cessation for household members of pregnant women, regardless of the mother's smoking status.
- Public health initiatives should focus on reducing environmental tobacco smoke exposure for pregnant women.
Background:
Childhood asthma development has been associated with active maternal smoking during pregnancy, but its association with maternal second-hand smoke exposure in pregnancy needs to be evaluated.
Objective:
We investigated longitudinal associations between maternal smoke exposure in pregnancy and childhood asthma development.
Methods:
In a population-based cohort of 5619 seven-year-old Toronto children, parents reported age of physician-diagnosed asthma development, maternal smoking during pregnancy, home second-hand smoke exposure from pregnancy until 7 years, demographics, and family history of atopy. By using Cox proportional and discrete-time hazard survival analyses, we evaluated associations between asthma and maternal smoking or home second-hand smoke exposure in pregnancy.
Results:
During pregnancy, 5.0% of mothers smoked and 6.2% were nonsmokers and exposed to home second-hand smoke; 15.5% of children developed asthma. Children whose mothers smoked or were exposed to home second-hand smoke during pregnancy were more likely to develop asthma (adjusted hazard ratio [HR] 1.30 [95% CI, 1.06-1.60]). The association persisted for children of nonsmoking mothers with home second-hand smoke exposure during pregnancy (adjusted HR 1.34 [95% CI, 1.01-1.76]), children with asthma symptoms in the past year (adjusted HR 1.36 [95% CI, 1.03-1.79]), and after adjusting for home second-hand smoke exposure from birth to age 7 years.
Conclusions:
Maternal home second-hand smoke exposure during pregnancy is associated with incident physician-diagnosed childhood asthma, even if the mother does not smoke actively during pregnancy. Childhood asthma prevention programs should include smoking cessation strategies targeted toward smokers who live in the homes of smoking and nonsmoking pregnant women as well as pregnant women who smoke.
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