New research has found that giving young babies a general anaesthetic has no lasting impact on their brain development or behaviour.

The study, published in the latest Lancet journal, looked at the effects of having surgery under an awake local anaesthetic compared to a general anaesthetic in 722 babies in 28 hospitals across seven countries.

Professor Andrew Davidson from the Murdoch Children's Research Institute, is one of the authors of the paper, 'Neurodevelopmental outcome at 5 years of age after general anesthesia or awake-regional anesthesia in infancy (GAS): an international, multi-centre, randomised controlled equivalence trial'.

Prof Davidson said the infants were all aged less than 60 weeks and underwent hernia operations (inguinal herniorrhaphies) between 2007 and 2013 in hospitals in Australia, Italy, US, the UK, Canada, the Netherlands and New Zealand.

About half the group (361 babies) received an awake localised anaesthetic while the other half, 359 babies, had a general (asleep) anaesthetic.

"Five years later the children were given a formal IQ test and there was no sign of any difference between the two groups," Prof Davidson said.

"Given the size and power of the trial it is therefore justifiable to conclude it shows evidence of IQ equivalence between the groups."

Prof Davidson, who is also with the Department of Pediatrics the University of Melbourne, said the children also underwent a series of behavioral, memory and attention assessments, and again there was no difference between the two groups.

"The research focused on very young babies because early infancy is a known to be a period of 'high cerebral vulnerability', when the brain is rapidly changing and developing," he said.

Prof Davidson said there are many animal studies that show anaesthetics can affect brain development and several previous human studies have found a link between surgery in childhood and later behavior problems or poorer academic achievement, but these human studies may be flawed due to inherent bias.

"Babies who have surgery often have other conditions which may explain the later issues," Prof Davidson said. "The only way to try to see if the anaesthetic is causing a problem was through such a trial."

Lead author Dr Mary Ellen McCann from the Boston Children's Hospital said the research demonstrated the strongest evidence to date that just under an hour of general anaesthesia in infancy did not cause clinically significant adverse neurodevelopmental outcome.

"The implications are that children who undergo an intermediate length anaesthesia in infancy start school life with no neurodevelopmental risk factors," Dr McCann said.

All children were tested within four months of turning five; the IQ scores of children aged between five and six years had a strong correlation with adult intelligence.

The five-year IQ follow-ups were carried out between 2012 to April 2018 using the Wechsler Preschool and Primary Scale of Intelligence – Third Edition – Full Scale IQ.

The behavioural assessments were the Wechsler Individual Achievement Test Second Edition (WIAT-II) or the BVN (the Italian equivalent of the WIAT-II), selected subtests of the Children's Memory Scale (CMS), the Global Executive Composite (GEC) of the Behavior Rating of Executive Function – Preschool Version (BRIEF-P), the Adaptive Behavioral Assessment System Second Edition (ABAS-II) and the Child Behavior Checklist Caregiver Questionnaire (CBCL).

Available for interview:

  • Professor Andrew Davidson

Media Contact

Christine Tondorf, MCRI Media Advisor

03 9936 6197 or 0413 307 092