Adults with a history of low birth weight are more prone to be hospitalized for breathing disorders than are adults without such a history, according to a new study.

Children born at low birth weights have been known to have abnormal lung function, according to the study's authors, but it has been unclear whether those effects linger until adulthood. The number of people born at such weights is not trivial: More than 330,000 fell into low birth weight or very low birth weight categories in 2005.

Dr. Eric C. Walter and associates at the University of Washington, Seattle, identified more than 4,600 people hospitalized for a respiratory illness between the ages of 18 and 27 years, and nearly 18,500 age-matched control subjects.

After adjusting for sociodemographics, the odds of hospitalization were significantly elevated, compared with those born with normal birth weight, for those with moderately low birth weight (birth weight 1,500-2,499 grams) and for those with very low birth weight (birth weight < 1,500 grams). Those born at moderately low birth weight were about 30 percent more likely to be hospitalized, while those born at very low birth weight were almost twice as likely — about 80 percent — to be hospitalized.

Asthma, lung infections such as pneumonia, and lung failure were more likely in those who had been both low birth weight and very low birth weight.

Dr. Walter's team estimates that low birth weight may account for more than 21,000 adult hospitalizations per year, at a cost of more than $225 million. They expect these estimates to rise as more and more low birth weight infants survive.

"If confirmed," the researchers conclude in their report in the American Journal of Respiratory and Clinical Care Medicine, "these findings suggest that internists, and not just pediatricians, need to be aware of their patient's birth history."