However, the warning was based largely on data from animals, which may or may not apply to children, said the researchers from Mayo Clinic in Minnesota.
‘Intelligence, memory and several other measures of brain function were similar among children who received anesthesia and did not.’
"For the majority of kids undergoing surgery, the results overall are reassuring," said lead author David Warner, a paediatric anaesthesiologist at Mayo Clinic.
"About 80 per cent of kids who need surgery under age three only need one and it's relatively brief," he added.
However, for those with multiple exposures to anesthesia had modest declines in fine motor skills, but their parents reported more learning and behavioural problems.
Parents whose children had anesthesia once under age 3 reported more problems with mental skills known as executive functions -- skills that help with memory, impulse control, planning and flexibility -- but not with other behaviours, the findings showed.
For the study, the team studied 997 people who had anaesthesia exposures before their third birthdays.
Beyond their anesthesia exposure, the three groups of patients were matched to be as similar as possible, the results revealed.
Several other studies also show little evidence that a single anaesthetic is associated with significant harm.
"Although we do have some concerns about the children who are receiving multiple anesthetics, it's important to note that our results don't allow us to conclude that anesthesia itself is causing problems," Warner said, adding that other factors, such as the conditions that make surgery necessary, could contribute.
"However, the fact that we found some problems in some of these children means that research in this area needs to continue, including further analysis of our data," he added.