Findings from the Columbia University Mailman School of Public Health, published in the journal Clinical and Experimental Allergy, suggest that younger children who have older siblings are more likely to experience respiratory symptoms and wheezing than those who were oldest or only-children. "Our findings support the hypothesis that having older siblings increases a child's risk of exposure to infectious agents before age two years, and in turn increases the child's risk for wheezing," said Mailman's Matthew Perzanowski. "Some studies have found that having older siblings increases the risk of wheeze in babies and toddlers. Our findings are novel in that we found that among the four year-olds in this study, the pattern was the same as has been observed in younger children elsewhere."
One possible explanation for the association is that children with older siblings have more exposure to respiratory infections at an early age than oldest or only children. Respiratory infections are a common cause of wheezing in very young children. This study shows that children with older siblings may be appropriate targets for interventions to reduce the risk of infections that may lead to hospitalization.
"Previous findings of the opposite association between asthma and birth order among older children and adults have served as the basis for what is called the hygiene hypothesis, the idea that exposure to infectious agents at a very young age reduces the risk of asthma in the long term. Only by continuing to follow these children can we determine whether and how birth order predicts diagnosed asthma and asthma that persists throughout childhood," noted Inge Goldstein, senior author of the study.
Related:
Environmental Toxins Behind Asthma?
Hormones Linked To Lung Function And Asthma
Digging The Dirt On Asthma
Source: Columbia University's Mailman School of Public Health
