“It’s no longer appropriate or useful to view the first years of life as a period to keep kids healthy and safe while allowing development to take its course until they are old enough to be educated,” said researcher Tim Moore, from the Royal Children’s Hospital’s Centre for Community Child Health.

Dr Moore told a hearing of the Productivity Commission’s inquiry into childcare that a significant body of evidence showed early experiences in the womb and during the first few years of life could change brain and neurological functioning.

Very young children learn and develop language and other concepts pre-consciously, he said: “It’s not just a matter of of waiting until kids are able to speak.”

This had implications for childcare, Dr Moore said: “As a society we’ve made commitments to hospitals, we’ve made commitments to school but we haven’t made any commitments to what goes on in early childhood.”

The commission has been asked to find ways to overhaul Australia’s convoluted childcare system as a way of encouraging more people – especially women – to return to work.

In its draft report, released in July, the commissioners recommended nannies and grandparents be paid by the government to look after children if they get a certificate III qualification – a minimum qualification many in the sector say is inadequate.

Frank Oberklaid, director of the Centre for Community Child Health, said that from the age of two or three, attending childcare had been shown to confer a “huge” advantage when the child reaches primary school.

Childcare could offer socialisation with other young children, with these opportunities “not as apparent” in other forms of care like nannying, Professor Oberklaid said.

At the hearing in Melbourne on Monday, early education expert Linda Harrison, from Charles Sturt University, said she feared the proposal that a certificate III in childcare would be the minimum for educators of children under three would mean a drop in quality.

Professor Harrison said her research showed childcare was of high quality and better on average than countries such as Britain and the US.

United Voice national secretary David O'Byrne, whose union who represents childcare workers, told the inquiry that proposed changes that would allow centres to comply with educator to child ratios “on average” across the week – rather than having a minimum ratio at all times – would compromise children’s development and safety.

Mr Byrne also said educators were leaving the industry because of poor pay and conditions.