The independent role of prenatal and postnatal exposure to active and passive smoking on the development of early wheeze in children

Abstract

Maternal smoking during pregnancy increases childhood asthma risk, but health effects in children of nonsmoking mothers passively exposed to tobacco smoke during pregnancy are unclear. We examined the association of maternal passive smoking during pregnancy and wheeze in children aged ≤2 years.Individual data of 27 993 mother–child pairs from 15 European birth cohorts were combined in pooled analyses taking into consideration potential confounders.Children with maternal exposure to passive smoking during pregnancy and no other smoking exposure were more likely to develop wheeze up to the age of 2 years (OR 1.11, 95% CI 1.03–1.20) compared with unexposed children. Risk of wheeze was further increased by children's postnatal passive smoke exposure in addition to their mothers' passive exposure during pregnancy (OR 1.29, 95% CI 1.19–1.40) and highest in children with both sources of passive exposure and mothers who smoked actively during pregnancy (OR 1.73, 95% CI 1.59–1.88). Risk of wheeze associated with tobacco smoke exposure was higher in children with an allergic versus nonallergic family history.Maternal passive smoking exposure during pregnancy is an independent risk factor for wheeze in children up to the age of 2 years. Pregnant females should avoid active and passive exposure to tobacco smoke for the benefit of their children's health.

Secondhand smoke exposure and risk of wheeze in early childhood: a prospective pregnancy birth cohort study

“…Recently, a pooled analysis of 15 European birth cohorts demonstrated that children exposed to prenatal tobacco smoking and both pre- and postnatal tobacco smoking were more likely to develop wheeze up to the age of two years compared with unexposed children [11]. The available evidence regarding the independent and additive effects of both pre- and postnatal smoking exposure on the risk of wheeze in children is limited, however, particularly in Asian populations.…”

What accounts for the association between late preterm births and risk of asthma?

“…Several other studies noted the importance of maternal smoking during pregnancy and the impact on the risk of asthma. [17][18][19][20][21] Smoking during pregnancy has been shown to increase the risk of preterm birth, which likely accounts for the difference of this confounder between the two cohorts in our study. 22,23 This confounder must be included in any study that assesses the association of preterm birth and asthma.…”

Maternal passive smoking and the risk of developing wheeze in children: how should we deal with it?

“…The risks are even higher when the mother shows pre-natal psychological stress [10]. It is known that wheezing may resolve spontaneously during childhood but may persist into adulthood, particularly in young children with severe asthma [11][12][13], but the question is, can we cut the risk or even prevent it?In this issue of the European Respiratory Journal, VARDAVAS et al [14] report the results of a pooled analysis of 15 cohort studies that participated in the European project ENRIECO (Environmental Health Risks in European Birth Cohorts) [15] to assess the independent effects of active and passive smoking exposure, both pre-and postnatal, on the development of wheeze in children before the age of 2 years. Furthermore, this study describes the development of wheeze in children based on the different sources of exposure and timeframes of pregnancy ( prenatal maternal active smoking, prenatal maternal passive smoking and children's postnatal passive smoking) and assessed them, both as independent and combined factors.…”

“…Despite the underreported smoking prevalence figures in pregnant women, the methods used in reporting the effects of tobacco exposure in the development of wheeze also played a role. Relying on parental report for measuring outcomes such as wheeze may be subject to underreporting and recall bias, which is acknowledged by VARDAVAS et al [14] as a study limitations.…”

“…We have learned from VARDAVAS et al [14] that maternal passive smoking during pregnancy is an independent risk factor for developing wheeze in children up to the age of 2 years. Could the study be used to support the current evidence about the importance of protecting both pregnant women and infants from SHS exposure, either in private or public areas?…”