Asthma, even in its milder forms, is increasingly unpredictable in children in cities, leading doctors to recommend more frequent monitoring.
A study by the Johns Hopkins Children's Center, led by researcher Hemant Sharma, suggests four or more check-ups could be a better hedge against flare-ups of wheezing and subsequent hospitalisation.
Current asthma guidelines in the US call for follow-up of one to six months after diagnosis, but six months may be too long for many patients, the researchers report in the November issue of Pediatrics.
"We know asthma is an unstable disease, but we underestimated just how unpredictably it could behave over time, especially in inner-city kids," said Sharma, a pediatric allergist at Hopkins Children's.
"Doctors and parents need to be more vigilant and schedule at least three-month check-ups even if the child appears to be doing fine."