Sydney, Researchers have found that people who had bronchitis at least once before the age of seven are more likely to develop lung problems in later life.

"However, the lung diseases they suffer from by the age of 53 were usually asthma and pneumonia rather than chronic bronchitis, said study author Jennifer Perret from the University of Melbourne in Australia.

The findings come from the Tasmanian Longitudinal Health Study, which followed 8,583 people who were born in Tasmania in 1961 and started school in 1968.

When the participants joined the study as children, the researchers investigated their lung function using a spirometer to measure how much air they could breathe out forcibly in one second and the total volume of air exhaled.

Their parents completed a questionnaire that asked whether the children had suffered asthma or bronchitis by the age of seven.

Childhood bronchitis was defined as a "loose, rattly or chesty cough". The participants were followed up for an average of 46 years.

The researchers categorised 3,085 participants into four groups: the reference group of those who never suffered from bronchitis before the age of seven (1,616 participants, 53 per cent), the non-recurrent group who had between one and five episodes (873, 28 per cent) lasting less than a month.

The recurrent group who had at least six episodes (555, 18 per cent) lasting less than a month, and the protracted recurrent group who had six or more episodes (41, 1.3 per cent) lasting an average of a month or more.

Compared to the reference group, people who had non-recurrent, recurrent or protracted recurrent episodes of bronchitis as children had a 1.4-fold, 2-fold and 3.2-fold increased risk of pneumonia, respectively.

By the time they reached the average age of 53; a 1.3-fold, 2.7-fold and 6.4-fold increased risk of ever suffering from asthma, respectively.

"The associations with asthma and pneumonia strengthened with increasing severity of childhood bronchitis," Perret said.

"However, there was no statistically significant link between childhood bronchitis and chronic bronchitis in middle-age. This was an unexpected finding and further study would be informative. We are currently exploring these associations," Perret added.

"Our findings strengthen the evidence that adult lung disease can originate in early childhood and that childhood bronchitis may adversely affect lung health in middle age," the study authors wrote.

The research was presented at the 'virtual' European Respiratory Society International Congress.