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Abstract: Background: Some human and animal studies have recently shown that maternal grandmother's smoking during pregnancy increases the risk of asthma in the grandchildren. We have investigated whether sex of the exposed parent and/or grandchild modifies the association between grandmaternal smoking and grandchild asthma. Methods: We formed a cohort study based on linkage of national registries with prospectively collected data over three generations. Smoking habits in early pregnancy were registered since 1982 and purchases of prescribed medication since 2005. In all, 10 329 children born since 2005 had information on maternal and grandmaternal smoking on both sides and were followed from birth up to 6 years of age. Ages when medication was purchased were used to classify the cohort into never, early transient (0‐3 years), early persistent (0‐3 and 4‐6 years), and late‐onset (4‐6 years) phenotypes of childhood asthma. Results: Maternal grandmother's smoking was associated with an increased odds of early persistent asthma after adjustment for maternal smoking and other confounders (odds ratio 1.29, 95% confidence interval 1.10‐1.51). Grandchild sex did not modify the association. Paternal grandmother's smoking was not associated with any of the asthma phenotypes. Conclusion: Maternal but not paternal exposure to nicotine before conception was related to an increased risk of early persistent childhood asthma, but not other asthma phenotypes. Our findings are possibly consistent with a sex‐specific mode of epigenetic transfer. [ABSTRACT FROM AUTHOR]

Low levels of secretory IgA (SIgA) and transient IgA deficiency have been associated with an increased risk for allergy, but data are conflicting. The aim was to assess the relationship between salivary SIgA antibody levels at 1 yr and wheezing at age four in a birth cohort, in particular the possible protective role of salivary SIgA in sensitized children. Saliva samples were obtained from all children (n = 67) with a positive skin prick test (SPT) at 1 yr and 212 children with a negative SPT. In all, 200 of these children responded to questionnaires at 4 yrs and 183 were skin prick tested at that age. The levels of salivary SIgA and salivary IgA antibodies to the most common food allergen egg and inhalant allergen cat were analyzed by ELISA. Serum was analyzed for IgE antibodies to egg and cat. Development of late-onset wheezing was associated with low SIgA levels in children with positive SPT to at least one allergen both at 1 and 4 yrs of age (p = 0.04), as well as in children with circulating IgE antibodies to egg or cat at 1 yr (p = 0.02). None of nine persistently sensitized children with SIgA levels in the upper quartile developed wheezing, when compared to 10/20 children with lower levels (p = 0.01). Older siblings, more than three infections during infancy, at least one smoking parent, and male gender, were all associated with SIgA in the upper quartile. In conclusion, high levels of SIgA antibodies in sensitized infants were associated with significantly less late-onset wheezing, supporting a protective role against development of asthmatic symptoms. Recurrent infections and other factors supporting an increased microbial pressure during infancy were associated with high levels of salivary SIgA. [ABSTRACT FROM AUTHOR]

Sandin A, Björkstén B, Bråbäck L. Development of atopy and wheezing symptoms in relation to heredity and early pet keeping in a Swedish birth cohort. Pediatr Allergy Immunol 2004: 15: 316–322. © 2004 Blackwell Munksgaard The role of pet keeping during infancy for the development of allergy and asthma is still controversial. The objective of this population-based birth cohort study was to assess the development of atopy and different wheezing phenotypes during the first 4 yr of life in relation to heredity and early pet keeping. The cohort comprised all 1228 infants living in a Swedish county who were born over a 1-yr period. The parents replied to repeated questionnaires and 817 of the children were skin prick tested both at 1 and 4 yr. Cat keeping during the first year of life was associated with an increased risk of a positive skin prick test to cat at 1 yr of age [odds ratio (OR) 2.2, 95% confidence interval (CI) 0.9–5.6], but neither with sensitivity nor clinical symptoms of allergy at 4 yr. Dog keeping during the first year of life was associated with an increased risk of early-onset transient wheezing, but only in children with parental asthma (adjusted OR 4.3, 95% CI 1.5–12.1). In contrast, early dog keeping had an inverse association with sensitivity to pollen allergen at 4 yr (adjusted OR 0.3, 95% CI 0.1–0.9) and late-onset wheezing (adjusted OR 0.4, 95% CI 0.2–1.0). Thus, pet keeping during the first year of life was not associated with an increased risk of atopy at 4 yr, although a positive SPT to cat was more common at 1 yr. Our findings may even suggest that dog keeping during the first year of life might provide some protection from pollen allergy and late-onset wheezing and increase the risk of early-onset transient wheezing in children with heredity for asthma. [ABSTRACT FROM AUTHOR]