Parental Smoking and Airway Reactivity in Healthy Infants

Abstract

Parental tobacco smoking is associated with lower airway function and an increased incidence of wheezy respiratory illnesses in infants. We evaluated in 76 healthy infants whether exposure to parental tobacco smoking was associated with airway hyperreactivity, which could contribute to lower airway function and the increased wheezy illnesses. Airway function was measured using the raised-volume rapid thoracic compression technique, and airway reactivity was assessed by methacholine challenge (0.015-10 mg/ml), which was stopped for a more than 30% decrease in forced expiratory flow (FEF)(75) or the final dose with a less than 30% decrease. Parental tobacco smoking was associated with lower baseline airway function (FEF(50), 600 vs. 676 ml/second, p < 0.04; FEF(25-75), 531 vs. 597 ml/second, p < 0.05). Infants exposed to tobacco smoking were approximately half as likely to develop a more than 30% decline in FEF(75) at any given methacholine dose (hazard ratio = 0.4, p = 0.001). In addition, a history of asthma in an extended family member increased the likelihood that an infant would develop a more than 30% decline in FEF(75) (hazard ratio = 1.7, p = 0.04). We conclude that exposure to parental smoking is associated with lower airway function but not increased airway reactivity; however, family history of asthma is associated with heightened airway reactivity.

Prenatal determinants of neonatal lung function in high-risk newborns

“…The comprehensive confounder adjustment of the current analysis validates previous reports of reduced infant lung function from the mother's smoking. 8,[27][28][29][30] We suggest that this Dashed lines show the 95% CIs. The median age at examination was 6 weeks (interquartile range, 5-8 weeks) with few subjects studied at the later time points, as reflected in the widening confidence limits.…”

Early Childhood Risk Factors for Decreased FEV1at Age 6-7 Years in Young Children with Cystic Fibrosis

“…Others have described cross-sectional (23)(24)(25)(26)(27) and longitudinal associations (18) between lower lung function and second-hand smoke exposure, but the effect of maternal smoking during pregnancy on lung function in children with CF has not to our knowledge been examined elsewhere. The effect of maternal smoking during pregnancy has been shown to be associated with lower lung function in healthy infants and adolescents and more symptoms in young children with asthma (28)(29)(30). Our results will need to be corroborated in other cohorts, but encouraging mothers known to be expecting a child with CF, for example, with positive results on prenatal screening, to stop smoking may provide benefit to later lung function.…”

Expired nitric oxide and airway reactivity in infants at risk for asthma

“…10-14 Several studies have evaluated whether the airway characteristics of heightened airway reactivity and increased levels of eNO are present early in life before the onset of asthma. Young et al, 15 as well as the members of our laboratory, 16 have reported that among healthy infants without prior episodes of wheezing, airway reactivity was greater in those infants with a family history of asthma or allergy compared with that seen in infants with a family history negative for these factors. Follow-up of the Perth infants found that heightened airway reactivity as an infant was associated with a diagnosis of asthma at 6 years of age.…”