A worldwide study of more than 1.5 million children found that the risk of developing asthma, or asthma-like symptoms, after a preterm birth is higher than previously thought. (Agencies)
In addition, the risks of developing asthmatic symptoms are the same for preschool and school-age children, indicating that children born prematurely do not outgrow the risk, a release by the University of Edinburgh said on Wednesday.
As an increasing number of babies now surviving premature birth and asthma being the most common chronic disease in childhood, it is likely to become a significant health problem.
Asthma affects some 8 per cent of children born at full term, while this rises to 14 per cent in babies born prematurely defined as at least three weeks early, the study shows.
Babies born more than three weeks before the usual 40-week term early 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 babies born at full term.
Data was taken from 30 studies of patients from six continents who were born since the 1990s. Most were from Western countries, including 14 from Europe and four from the UK.
Many premature babies experience breathing problems, because their lungs are immature.
The findings were published in medical journal called PLOS Medicine.
Previous research among premature babies born in the 1960s to 1980s showed that many went on to develop asthma.
Although care for preterm babies has improved, it was unclear whether this affected the babies' long-term risk of asthma.
"Doctors and parents need to be aware of the increased risks of asthma in premature babies, in order to make early diagnosis and intervention possible," said Dr Jasper Been, of the University of Edinburgh's Centre for Population Health Sciences, who led the study in collaboration with Maastricht and Harvard Universities.
"We know that uncontrolled asthma in pregnant women, amongst other things, can increase the risk of premature birth, which reinforces the need for good asthma management during pregnancy," said Dr Samantha Walker, Executive Director of Research and Policy at Asthma UK.
A worldwide study of more than 1.5 million children found that the risk of developing asthma, or asthma-like symptoms, after a preterm birth is higher than previously thought.