PURPOSE OF THE STUDY.
To examine the associations between high BMI and changes in BMI during the first 7 years of life and asthma and allergic sensitization at age 8 years.
A birth cohort of 2075 newborn infants followed for 8 years in Sweden as part of a broader prospective epidemiologic study of atopic families (the BAMSE study).
Parental questionnaires provided information about environmental exposures and health outcomes including allergic disease and asthma. Allergic sensitization was determined by assessing allergen-specific IgE to dust mites, cat, dog, horse, Cladosporium, birch, timothy, mugwort, milk, egg, codfish, soy, peanut, and wheat. Height and weight data during the study period were obtained from preschool and school health care records.
A high BMI (≥85th percentile) at age 1, 4, and/or 7 years of age was associated with an increased risk of asthma at age 8 years. No such association was observed among children with high BMI at 12 and/or 18 months or at 4 years who developed a normal BMI by age 7 years. The risk was increased among children with high BMI at age 7 years regardless of their earlier weight. Increased risk of sensitization to inhalant allergens was also observed in children with high BMI at age 7 years.
High BMI during the first 4 years does not increase the risk of asthma at school age among children who have normal weight by age 7 years. High BMI at 7 years is associated with an increased risk of asthma and sensitization to inhalant allergens at age 8 years.
This study adds further evidence that current elevated BMI is associated with asthma, whereas previous elevations of BMI are not. These results are similar to those of a previous Dutch study (Scholtens S et al. J Allergy Clin Immunol. 2009;123:1312–1318). This observation suggests that obesity is not causative for asthma per se but likely an important inflammatory modifier. Previous studies suggest that leptin, an adipocyte-derived hormone, may upregulate inflammatory immune responses in general and thus could amplify asthma, a chronic inflammatory airway disease. This study also documented an increased risk of sensitization to inhalant allergens among children with a high BMI at 7 years; this association was not seen for food allergens. Although not proved in this study, it is also plausible leptin could play an important role in this pathway through hormone-specific receptors on a variety of cells, including eosinophils.
- Copyright © 2012 by the American Academy of Pediatrics