Breastfeeding mothers are OK, it seems, but the parliaments of Australia are divided over how to deal with the next frontier in family-friendly workplaces – noisy toddlers.

The federal House of Representatives broke new ground in March, changing its rules to allow small children onto Parliament's floor, in response to a spate of tiny, illicit "visitors" appearing with male and female MPs during urgent votes. Traditionally, no one other than an MP can enter.

But a request by NSW Labor MLC Courtney Houssos​ to extend the same flexibility to state MPs has split parliamentary ranks.

The president of Western Australia's Legislative Council, Barry House, has written to his NSW counterpart, Don Harwin​, to say developments allowing babies and children into the chamber "appear undesirable to me".

Mr House fears juvenile interruptions and the erosion of Parliament's exclusivity. He says the four working parents in his Parliament "admirably balance" their roles "without any disruption to proceedings".

The speaker of the NSW lower house, Shelley Hancock, wrote: "Common sense dictates that the chamber, similar to a court of law, is not an arena conducive to quality child care."

While breastfeeding infants have been allowed into parliaments since 2003, after outrage at the eviction of Victorian MP Kirstie Marshall and her 11-day-old baby, no state parliament technically allows an infant who is not breastfeeding.

Ms Houssos, 32, wants standing orders in the NSW upper house changed so that children under four years can briefly accompany a parent to vote during a division, when MPs are expected to drop everything and rush to the chamber.

An incident in 2015, when the division bells rang unexpectedly at night while Ms Houssos was holding her 19-month-old daughter Anna when her husband was in another part of the building, has sparked a NSW inquiry into the issue.

Traditionally, MPs are offered a "pair" to abstain from voting, but Ms Houssos says parents should be able to vote, by proxy or by entering the chamber with their child.

Proxy voting was introduced to the federal lower house in 2008 for breastfeeding women and has been used 34 times since.

"The nature of Parliament is that it has long sitting hours, often late into the night," says Ms Houssos.

"The private sector is increasingly making flexible working arrangements to allow workers to better balance their family and work responsibilities."

She says the demographics of Parliament are changing, and it was time to "take small steps" and "send a powerful message that Parliament supports its members".

But not everybody is convinced.

NSW Treasurer Gladys Berejiklian​ told Fairfax Media: "I would support measures to make Parliament more family friendly, including more childcare options near or at work, but I believe this could be achieved without major changes to standing orders."

Mr Harwin has written to the other states, and international parliaments, for their views.

"We were one of the first houses to change standing orders in relation to breastfeeding of infants, and others followed. Now we just want to see what else, if anything, should be done," he said.

Tasmania and the ACT replied that children wouldn't be allowed onto the floor, and the ACT last month rejected proxy voting.

Queensland's speaker Peter Wellington said no MPs had requested to bring infants into the chamber, and the only visitors who had been allowed were Sir Peter Cosgrove, and the Prime Minister of Papua New Guinea, Sir Michael Somare.

But the Northern Territory said it will adopt proxy voting for breastfeeding women during a division.

The House of Representatives said its recent changes were guided by "pragmatism and goodwill" towards working parents.

But although the Senate is considering similar reforms, Senate President Stephen Parry said he believed proxy voting was unconstitutional, and there are "issues" with allowing infants who are not breastfeeding into the chamber.

These included "the question of equity – is there sufficient basis to distinguish between senators with different needs?"

Ms Hancock said NSW MPs have brought babies or toddlers into the lower house as a "one-off".

"I accept that on the odd occasion parents may need to bring their babies into the chamber but would encourage members of the Legislative Council to ensure where possible alternate childcare arrangements are made during a division," she said.

The Welsh parliament reported that an MP once brought a child into the chamber in 2005, and it was not commented on. The Scottish Parliament wasn't aware of any request.