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

• Published in: Pediatric allergy and immunology Vol. 20; no. 1; pp. 30 - 34
• Main Authors: Guedes, H. T. V., Souza, L. S. F.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2009; Blackwell
• Subjects: allergy; asthma; Biological and medical sciences; Breast Feeding; Child, Preschool; Cohort Studies; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Infant; Infant, Newborn; Inhalation Exposure - adverse effects; Logistic Models; Male; Medical sciences; Mothers; passive smoking; Prospective Studies; Respiratory Hypersensitivity - epidemiology; Respiratory Hypersensitivity - immunology; rhinitis; Risk Factors; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Smoking - adverse effects; Lung disease; Allergy; Immunopathology; Pediatrics; Nose disease; breast-feeding; Rhinitis; Respiratory disease; Protective factor; Exposure; Breast feeding; Birth; Respiratory system; Asthma; Immunology; Age of onset; Mother; Passive smoking; ENT disease; Bronchus disease; Obstructive pulmonary disease; Protection
• ISSN: 0905-6157; 1399-3038
• DOI: 10.1111/j.1399-3038.2007.00710.x

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.