Babies born with a low birth weight are not at an increased risk of going on to develop asthma, a new study indicates.

According to US scientists, while genetics and the environment are thought to play a role in the development of the condition, the actual cause of asthma remains unknown. However, having a low birth weight can be removed from possible causes, it appears.

"Asthma is the most common chronic illness in childhood and is a leading reason for missed school days. While environment, genetics, and their interaction are thought to increase one's risk of developing asthma, we now should not assume that low birth weight is associated with asthma," the scientists said.

They studied almost 4,000 children born in an area of the US between the beginning of 1976 and the end of the 1979. They found that just over 5% of those who were a normal weight at birth went on to develop asthma, while just over 6% of those with a low birth weight developed the condition.

The scientists concluded that birth weight had no role to play in the development of asthma within a child's first six years of life.

"Asthma is a lifelong disease that is increasing every year, both by the number of people affected and by the cost. This is an important finding as we continue to understand who is at risk for asthma and why," they commented.

Details of these findings are published in the journal, Annals of Allergy, Asthma and Immunology.

One in five Irish children have asthma. For more information on the condition, see our Asthma Clinic here