Babies and toddlers who went under anesthesia during surgery ended up having slightly worse scores on language and reasoning tests as 10-year-olds, in a new study.
That doesn't prove the anesthesia is to blame, researchers pointed out.
"At this point, we're still unsure if these differences are due to anesthesia, surgery or some other factor, like the underlying diagnosis that caused kids to need surgery in the first place," said lead researcher Dr. Caleb Ing, an anesthesiologist from the Columbia University Medical Center in New York.
And even if anesthesia proves to be behind the extra risk of learning problems, it's still important for many surgeries in kids, researchers said.
Doctors already know putting kids to sleep carries a small risk of breathing complications - and they're accustomed to weighing possible risks with the benefits of a procedure that requires anesthesia.
"The vast majority of procedures we do on kids of this age, we don't do lightly," said Dr. David Warner, an anesthesiologist from the Mayo Clinic in Rochester, Minnesota.
Surgeries to relieve inner ear pressure, hernia procedures, circumcisions and tonsillectomies were the most common reasons kids in the new study received anesthesia.
The data was collected from records of about 2,600 kids born in Australia between 1989 and 1992. Of those, 321 went under anesthesia at least once before age three.
At age 10, all kids in the study were given a battery of tests measuring their thinking, language and motor skills as well as behavior issues.
There were no differences in behavioral problems or motor function based on whether or not kids had needed anesthesia as babies and toddlers, according to findings published Monday in the journal Pediatrics.
But kids who'd had anesthesia were about twice as likely to show signs of language disabilities and 70 percent more likely to have reasoning problems than the non-anesthesia group.
The researchers counted a "disability" as a score in the seventh percentile or lower on the standardized tests.
Studies in baby animals have shown that anesthesia can cause some brain cells to die and may affect the formation of circuits that other neurons use to communicate. But it's still not clear whether that also happens in kids' brains, researchers noted.
Based on the new study, it's difficult to say if the average difference in learning and reasoning between the two groups is one that a parent or teacher would notice in the average child, Warner said.
Still, he added that combined with other research linking multiple rounds of anesthesia with learning disabilities and attention-deficit hyperactivity disorder, the effect "may in fact be clinically significant."
What this study adds, Warner pointed out, is that even kids who underwent anesthesia only once when they were very young still had more trouble later on.
Nonetheless, "Our results do not mean that children should not have surgery if it's needed," Ing told Reuters Health.
Warner, who wasn't involved in the new study, agreed.
"Even though there is an increase in risk, the vast majority of kids don't have problems (after anesthesia)," he told Reuters Health.
For example, 30 out of 214 kids who'd gone under anesthesia had very low scores on the language test.
"We don't want parents to be unduly alarmed, to prevent their children from having necessary surgery. But we can't be entirely reassuring that there aren't any long-term effects, especially from having multiple anesthetics," Warner said.
Ing said studies currently underway are testing whether there's a difference in the long-term effects of local and general anesthesia.
But for now, he added, "We don't have enough evidence to change our current medical practice."