Children’s hospitals across Canada are advising parents not to delay necessary surgeries out of fears raised by a U.S. Food and Drug Administration warning that repeated or lengthy exposure to general anesthesia may harm brain development in children under 3.

The FDA warning, issued in December, has drawn criticism from doctors who say it is based on inconclusive data and may cause undue alarm among parents of children who must undergo general anesthesia.

“Right now, there is really no strong evidence that we should delay surgeries because of the anesthetic risk,” said Dr. Jason Maynes, director of research in anesthesia and pain medicine at the Hospital for Sick Children in Toronto, Canada’s largest pediatric hospital.

Findings from two major Canadian studies, both published in 2016, show no increased risk of learning or behavioural problems in infants and toddlers exposed to general anesthesia.