Premature baby in incubator
People who are born prematurely can be at increased risk for some lung diseases. Illustration photo: Colourbox

Being premature can increase your risk of COPD and asthma

“Doctors should look at the length of pregnancy in patients with respiratory problems,” says researcher Kari Risnes. But if you were born before your due date, you can take some measures yourself to prevent lung infections.

Shortening the pregnancy by a few weeks can have an impact on lung health.

“Doctors must become more aware of this,” said Kari Risnes, a professor at NTNU and a senior physician at St. Olav’s Hospital.

She is behind a new study which shows that the risk of developing chronic lung disease is significantly higher for those born before term, even in adulthood.

“What we found supports previous findings that show an increased incidence of lung disease in childhood for this group. But no one has previously reported on the incidence of severe lung disease in adults in relation to how premature their birth was. This is new,” Risnes said.

Premature baby on scale

It’s not always the best to be small. It can be extra tough if you are born prematurely. Illustration photo: Colourbox

Vulnerable group

It’s long been known that prematurely born children have an increased mortality in childhood and early adulthood.

In 2021, Risnes and her colleagues showed how the risk of dying from heart disease, chronic lung disease and diabetes follows this group into adulthood.

Now the researchers have taken a closer look at the incidence of asthma and lung diseases such as COPD (chronic obstructive pulmonary disease) in this group.

“What we see is that the risk of developing chronic lung disease is significant, even in adulthood,” Risnes said.

In their study “Preterm birth and asthma and COPD in adulthood: A nationwide register study from two Nordic countries“, which was published earlier this year in the European Respiratory Journal, the NTNU researchers used data from nearly 2.4 million people born in Norway and Finland in from 1967 to 1999.

Approximately five per cent were born prematurely, that is, before week 37 of the pregnancy. Thirteen per cent were born at what the researchers call “early term”, that is in weeks 37 and 38.

“We have used data for patients who have been ill enough to have been diagnosed either in hospital or by private specialists,” Risnes said.

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Concerned about COPD incidence

The figures show that all premature babies, including children born as late as week 38 of pregnancy, have a higher risk than full-term children of developing asthma.

But what worries the researchers is that they also have a higher risk of developing COPD, which is a more serious disease than asthma.

“This shows that it is important to prevent lung infections in this group. Asthma is not always a serious illness, and many people can live well with asthma today. But COPD is a serious disease that severely limits life,” says Risnes.

COPD is still a rare disease compared to asthma, also in premature babies.

“But the excess frequency in premature children is stronger for COPD than for asthma. This applies to children born right up to full term,” says Risnes.

She believes doctors need to be more aware that even shortening the pregnancy by a few weeks can have an impact on lung health.

“There has always been a lot of attention around those born extremely early, but these make up a very small group. We now see that there is an increased risk of disease also in babies born towards week 37-38. Doctors have to start to see this as a risk factor,” she said.

Immature lungs before term

In other words, the length of pregnancy can be an indicator that can be used to decide whether to start investigation and treatment of adults with respiratory problems.

Kari Risnes

Kari Risnes. Photo: NTNU

“Doctors need to start asking about the length of pregnancy, and pay attention to previous diagnoses such as asthma. It is important to get treatment that protects the lungs over the long term,” says Risnes.

While the child is in the mother’s womb, it is the placenta that acts as the child’s “lungs”, and in premature babies, the lungs have to take over the function of the placenta before they are fully ready.

If the lungs are too poorly developed, the child has to be given mechanical breathing support after birth, a treatment that previously could damage the lungs.

“In the foetal stage, the lungs develop slowly, right up to term. As long as the child is in the uterus, the lungs are closed, and when the child is born, the lungs must suddenly start doing their job. Then it doesn’t take much for them not to function as they should. The more immature the lungs are, the more often the child must be put on a ventilator,” she said.

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Vaccination and stopping smoking important

Thirty or 40 years ago, the technology used for ventilators could damage newborn lungs. But in recent decades, pulmonary treatment of prematurely born children has improved significantly. For that reason, Risnes doesn’t rule out the possibility that there will be a change in the incidence of lung disease as new generations grow up.

“Previously, the lungs of the newborns were damaged by the treatment. Today, we have completely different lung medicines and we have much better methods to support lung function. This probably means that we will have less of the most serious lung diseases. But the data here is not clear-cut,”  Risnes said.

She believes the incidence of COPD and other serious lung diseases is worrying.

“If you know you were born too early, whether a lot or a little, precautions should be taken. For example, smoking is harmful, and you should get vaccinated to prevent lung infections. You should ensure that your lungs are in the best possible condition, “says Risnes.

Reference: Preterm birth and asthma and COPD in adulthood: a nationwide register study from two Nordic countries. Anna PulakkaKari RisnesJohanna MetsäläSuvi AleniusKatriina HeikkiläSara Marie NilsenPieta Näsänen-GilmorePeija HaaramoMika GisslerSigne OpdahlEero Kajantie