Babies born prematurely are more likely to develop childhood asthma than those who reach full term, Scottish researchers have found.
The worldwide study of more than 1.5 million children found that the risk of developing asthma, or asthma-like symptoms, after a pre-term birth was higher than previously thought.
The research also discovered that the risk of developing asthmatic symptoms was the same for pre-school and school-age children – showing that children born prematurely did not outgrow it.
Campaigners said uncontrolled asthma in pregnant women could also increase the risk of premature birth, meaning it was vital they used their medication.
In Scotland, about 368,000 people – 1 in 14 of the population – receive treatment for asthma, including 72,000 children.
The latest study by Edinburgh University found that asthma affects 8 per cent of children born at full-term. But this rises to 14 per cent in babies born prematurely, defined as at least three weeks early.
The researchers, writing in the journal PLOS Medicine, said that, with asthma the most common chronic disease in childhood, and an increasing number of babies now surviving premature birth, this was likely to become a significant health problem.
Babies born more than three weeks before the usual 40-week term were almost 50 per cent more likely to develop asthma. Those born more than two months early were three times as likely to be affected as full-term babies.
The researchers used data taken from 30 studies of patients from six continents who were born since the 1990s. Most of the studies were from western countries, including 14 from Europe and four from the UK.
The researchers said it was important to better understand why pre-term birth leads to asthma, so that early treatments could be developed to prevent childhood asthma among these children.
Dr Jasper Been, from Edinburgh University’s Centre for Population Health Sciences, who led the study in collaboration with Maastricht and Harvard Universities, said: “By changing the way we monitor and treat children born pre-term, we hope to decrease the future risks of serious breathing problems, including asthma.”