Children who have brothers or sisters have a lower asthma risk than children who have no siblings, according to a Canadian study.

The Study

Researchers followed up 170,960 children from birth to age 6. In total, 14.1% of the newborns were seen by a doctor for asthma. The highest incidence of asthma was in the first two years of life.


The study found that children of multiple births and children who had siblings had a lower asthma risk than children who did not have siblings.

Interestingly, children born from July through December had a greater asthma risk than children born from January through March.

The risk of asthma increased if newborns were male, lived in an urban area, were born prematurely, had a low birth weight or their primary-care provider was a pediatrician.

Other risk factors included having a maternal or sibling history of asthma, exposure as an infant to upper- or lower-respiratory tract infections and the presence of congenital conditions, such as respiratory distress syndrome or cystic fibrosis.

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