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Preterm birth linked to asthma and wheeze

Children born very preterm have three times higher risk than full-term babies

Louise Prime

Wednesday, 29 January 2014

Children who were born before 37 weeks’ gestation have a much higher risk than those born at term of developing asthma or a wheezing disorder, and the risk is much further increased for those born before 32 weeks, research has shown. Authors of the study*, published today in PLOS Medicine, also found that the excess risk did not diminish as children grew older.

Researchers in Maastricht, Edinburgh and at Harvard Medical School conducted a meta-analysis of 30 epidemiological studies that they had identified, which had investigated the association between preterm birth and asthma or wheezing disorders. These studies included more than 1.5 million children in total.

They found that children who had been born preterm, ie before 37 weeks’ gestation,
were about 46% more likely than those born at or beyond 37 weeks to develop asthma or a wheezing disorder during childhood. The relative risk was considerably higher for those born very preterm, before 32 weeks – they were almost three times more likely than term babies to go on to have asthma or wheeze.

The researchers also found that the association persisted up to 18 years. They wrote: “The current findings do not support prior suggestions that the association between preterm birth and wheezing disorders becomes less prominent with increasing age. Instead, the strength of the association was similar across age groups, suggesting that the pulmonary consequences of preterm birth tend to persist throughout the life course.”

They estimate that there would be 3.1% fewer cases of childhood wheezing disorders if no preterm births had occurred. They suggest that because about 11% of surviving children are now born preterm and the proportion is expected to increase globally, more research is needed into this association – and into preventive interventions.

They conclude: “There is compelling evidence that preterm birth – particularly very preterm birth – increases the risk of asthma. Given the projected global increases in children surviving preterm births, research now needs to focus on understanding underlying mechanisms, and then to translate these insights into the development of preventive interventions.”

*PLoS Med 11(1): e1001596. doi:10.1371/journal.pmed.1001596

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