Asthma is more of a risk for young adults who were born very premature, according to a report published in the journal Pediatrics.
The study looked at data from over 600,000 Swedish adults born in the 1970s and found that those born very early between the 23rd and 27th weeks of pregnancy were more than twice as likely to have asthma as young adults born full-term.
The findings are "somewhat unexpected," said lead researcher Dr. Casey Crump, an assistant professor of medicine at Stanford University in California. Generally, he said, previous research has indicated that respiratory problems after preterm birth go away during childhood.
The findings are based on data for all 622,616 infants born in Sweden between 1973 and 1979. Four percent were born prematurely, and 9 percent of those had asthma drug prescriptions at some point between 2005 and 2007.
However, the results do not prove that very early birth, itself, leads to asthma in some adults. But Crump says the connection makes sense.
"Preterm delivery can result in immature lung development, altered immune function that is needed for normal lung function, and increased susceptibility to infection or environmental factors such as smoking," he explained.
Crump said that parents of very preterm children should be aware of the risk, which involves having respiratory problems examined thoroughly. Furthermore, it's "very important" that young people avoid smoking, which would boost any increased asthma risk.
