Australia has one of the highest rates of babies being treated with antibiotics, research shows.
Analysis of the Barwon Infant Study - a birth cohort study being conducted as a partnership between the Murdoch Children's Research Institute, Barwon Health and Deakin University - has found half of infants were treated with antibiotics during their first year of life.
One in eight received three or more antibiotic prescriptions.
The study, published in the Journal of Paediatrics and Child Health, found a concerning number were prescribed unnecessarily.
At least 20 per cent of prescriptions were for viral infections, which don't respond to antibiotics.
Researchers say the antibiotic prescription rate is almost 150 per cent higher than the UK and almost 500 per cent higher than Switzerland.
"Australian babies in this large study were exposed to considerably more antibiotics than the majority of their international counterparts," lead author Professor David Burgner said.
He's called for interventions to support GPs and parents to avoid unnecessary courses of antibiotics.
"Managing babies with infections in the community is difficult but it is important to recognise that the vast majority of these illnesses are viral and that antibiotics won't help," Professor Burgner said.
"The high rate of antibiotic exposure is concerning given increasing antimicrobial resistance and the reported association with chronic diseases, including asthma and childhood obesity."