New York, April 30 (IANS): By the time they reach their early 20s, adult survivors of premature births may have a lung capacity that resembles the healthy elderly or casual smokers, says a study. 

The researchers compared the lung function of adults who were born at less than 32 weeks gestational age to adults born full-term.

The study found premature infants are at increased risk for contracting bronchopulmonary dysplasia (BPD), a chronic respiratory condition mainly affecting infants born less than 28 weeks of age.

The researchers looked at three groups: 20 adults born prematurely with BPD, 15 adults born prematurely without BPD and a control group of 20 healthy adults born full-term.

All went through a series of tests designed to examine lung function during exercise.

The study suggests that adults born prematurely without BPD, like their counterparts with BPD, show symptoms of a mild form of chronic obstructive pulmonary disease (COPD), a progressive disease that makes it harder to breathe, in their mid-20s.

Their lungs did not function as efficiently as the control group, which caused them to tire sooner.

"We were expecting more variation between the two preterm groups -- with and without BPD," said Andrew Lovering, professor of human physiology at the University of Oregon.

"We did not anticipate that they would share a similar lung profile," Lovering noted.

COPD, commonly known as smoker's lung, is a fairly common condition, affecting 329 million people worldwide.

Even if the rate of decline in their lung function remains normal throughout their life, adult preterm survivors with COPD will likely develop respiratory complications at a much younger age, Lovering said.

"Additional research is needed to find better ways to serve adult survivors of preterm birth," Lovering noted.

The study appeared in the journal Annals of the American Thoracic Society.