title: Exposure to maternal smoking in the first year of life interferes in breast-feeding protective effect against the onset of respiratory allergy from birth to 5 yr.
abstract: The aim of this study was to evaluate the interaction between the exclusive breast-feeding protective effect and the exposure to tobacco smoke at domicile in the first year of life, on the onset of respiratory allergy (asthma and rhinitis) in children until 5 yr of age. This is prospective cohort study, observational, institutional based. Three hundred children born in a public hospital of Salvador-Bahia (Brazil) were followed from birth to 5 yr of age. Data from 268 children at 60 months of life were analyzed. Occurrence of allergic symptoms were studied and correlated with gender, allergic relatives in first degree, exclusive breast-feeding duration, smoking mother, and presence of other smoker at home, considering the first year of life. Exclusive breast-feeding for at least 6 months showed a protection effect against the onset of respiratory allergy in children from birth to 5 yr (p < 0.05); odds ratio (OR): 0.33 (95% CI: 0.18-0.59). Breast-fed children for less then 6 months compared with those breast-fed for 6 months or more, presented a higher risk (OR: 2.34-95% CI: 1.4-3.74) for developing allergic respiratory symptoms just to 5 yr. The protective effect of exclusive prolonged breast-feeding on the onset of respiratory allergy in children from birth until 5 yr was lost when their mothers were smokers (OR: 2.50-95% CI 1.19-5.19). Therefore, the protective effect of breast-feeding in the first year of life on the onset of allergic symptoms until the age of 5 yr was confirmed. This study proposes a confounding effect of maternal smoking on this protection, exposed by a higher risk for present allergic symptoms until the age of 5 yr, in children exclusively breast-fed for 6 months or more, when their mothers smoked.
authors.affiliation: School of Medicine-Salvador, Bahia, Brazil. hermila.guedes@gmail.com
authors.forename: H T V
authors.initials: HT
authors.lastname: Guedes
authors.forename: L S F
authors.initials: LS
authors.lastname: Souza
mesh_terms: D001942:Breast Feeding; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019570:Inhalation Exposure / Q000009:adverse effects*; D016015:Logistic Models; D008297:Male; D009035:Mothers; D011446:Prospective Studies; D012130:Respiratory Hypersensitivity / Q000453:epidemiology* / Q000276:immunology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*