Being a first born child has been found to increase the risk of asthma, while cat ownership appears to lower the risk
|A new study has found that children who grow up with cats in the home may be less likely to develop asthma, while another study has found first born children are more likely to develop the condition.
Researchers discovered that children who grow up with cats were more likely to have had made antibodies to cats early in life and were more likely to have wheeze, a respiratory symptom associated with asthma. However, by the age of five these children were then found to be less likely to have wheeze.
"While the study design does not allow us to recommend early cat ownership to prevent asthma, it does seem to indicate that avoidance of cats to prevent the development of asthma is not advised.
However, once a child has asthma and is allergic to cats, the recommendation would still be to find a new home for the cat," said Matthew Perzanowski, assistant professor of Environmental Health Sciences at the Mailman School of Public Health and lead author and investigator on the research.
Further research by an American team working in England has discovered that first born children are more likely to develop asthma than their later siblings.
The researchers detected samples of blood from the umbilical cord among 1,200 newborn babies from the Isle of Wight. They measured a chemical known as IgE, which is an indicator of how well the immune system functions and plays a key role in the development of allergic responses.
First born babies were more likely to have high levels of IgE, and those that did had a 67 per cent increased chance of having a positive skin prick test at four and were twice as likely to have a reaction at ten years of age. However, this was not true for second or third born children.
Dr Wilfried Karmaus, of the University of South Carolina, said: "Our findings add to the evidence that allergic reactions are programmed during pregnancy and then effect the disease in later life.
"This finding may partially account for the increasing prevalence of asthma and allergies in children in the last 30 years, primarily seen in the western world, as developed nations' birth rates continue to decline."