Less than one hour of general anaesthesia in infancy has no lasting impacts on children’s brain development or behaviour, according to the first randomised controlled trial to investigate such outcomes.

The trial compared neurodevelopmental outcomes at age five among 700 mostly male infants, who had been randomised to receive either spinal anaesthesia or general anaesthesia for hernia operations at a mean age of 10 weeks.

The study, spanning 28 hospitals in seven countries including Australia, showed that a brief episode of general anaesthesia in infancy was unlikely to harm long-term neurodevelopment, the researchers said.

The children’s IQs at age five were deemed “equivalent”, with a mean difference of 0.23 on the Wechsler Preschool and Primary Scale of Intelligence, according to the findings published in the Lancet.