MONDAY, June 4 (HealthDay News) -- If taking your infant to swim class seems like a fun way of bonding-with-baby, you might want to think twice about the idea.

That's because a new European study has found that infants who were regularly exposed to the chlorinated air of indoor swimming pools were more at risk for developing asthma than were infants who didn't swim indoors.

"Our data suggest that infant swimming practice in chlorinated indoor swimming pools is associated with airway changes that, along with other factors, seem to predispose children to the development of asthma and recurrent bronchitis," wrote the Belgian researchers. They also found the effect was stronger for babies who swam indoors and were also exposed to environmental tobacco smoke.

The findings appear in the June issue of Pediatrics.

The researchers surveyed 341 schoolchildren from Brussels and their parents. At the time the study began, the youngsters were between the ages of 10 and 13. The children and their parents were asked about their asthma status, other environmental exposures, and whether or not they had gone to indoor swimming pools as infants.

Forty-three children from that group had regularly been to indoor swimming pools in their infancy, according to the study. The children had to have had at least 2.5 cumulative hours on indoor pool exposure to be included in this smaller group.

Blood samples were taken from the children to measure markers of lung health, and average air sample tests were obtained from the pools the youngsters visited.

The researchers found that children who went swimming indoors as infants were 50 percent more likely to report wheezing, almost four times as likely to experience chest tightness, and had more than double the risk of experiencing shortness of breath, compared to the children who hadn't been regular swimmers as infants.

The study also found that exposure to passive smoke alone didn't seem to increase a child's risk of asthma, but when coupled with indoor swimming, the risk of developing lung problems was even higher.

The study authors suggest that the risk might be higher because exposure to chemicals, such as chlorine, may alter the lining of the lungs, predisposing youngsters to airway disease.

Does that mean you can't ever take your baby swimming?

"It certainly makes us reconsider taking these young kids swimming if it may be detrimental to lung development," said Dr. Alan Khadavi, a pediatric asthma specialist at New York University Medical Center in New York City. "But it's a small study, so I think it's too soon to tell parents that they can't take kids swimming. It's something to think about, but there's no direct link at this point."

While disinfection of swimming pools with chlorine is essential for safe swimming, study author Alfred Bernard, the research director of the National Fund for Scientific Research in Belgium, said that parents and pool managers should be aware that chlorine-based disinfectants can be used safely only if their levels are maintained in an optimal range which allows the chlorine to minimize infections without increasing the risk of toxicity.

"If levels are too low, infectious risks can increase, and if levels are too high, it is the toxic risks that can increase. Hence, the importance of hygiene and of carefully controlling the pH of the water to minimize the amount of chlorine needed for disinfection. Chlorine should not replace water filtration and hygiene to achieve a clear and blue water. Chlorine should only be used as a disinfectant and not a cleaning agent," advised Bernard.

"If [swimming] is a regular activity, I can only recommend parents don't take their baby in poorly managed pools where water and air contain excessive levels of chlorine. Such pools can be identified by the very strong chlorine smell in the air or at their surface as well as by the irritating effects on the eyes or upper respiratory tract that one may feel after swimming. If it is [your] own pool, parents should avoid over-chlorinating the water," he added.

"It is important to realize that studies on the safety of these chemicals for young children have started only recently. Thus, another cautious attitude for babies is not to leave them too much time in the water," Bernard said.

He also recommended that kids should swim no more than 20 minutes and that parents should discourage infants and young children from drinking pool water.

More information

For other advice on preventing asthma in children, visit the American Academy of Allergy, Asthma and Immunology.