Childcare centres have dumped places for babies, leaving families on waiting lists for up to two years.
Research commissioned by the Australian Greens of 231 private and community day-care centres shows the availability of childcare places has dropped nationally by 10 per cent in the past three years.
Three out of four childcare centres that offer long day care have zero vacancies for babies.
Two thirds have no places for toddlers.
Australian Greens senator Sarah Hanson-Young said Australia was on the "cusp of a childcare crisis."
"We've heard stories of mothers putting themselves on waiting lists (for childcare) while they're still pregnant," she told reporters in Adelaide on Sunday.
"By the time they need the spot, the spot is still unavailable."
Tuesdays, Wednesday and Thursdays were the high demand days, she said when there were hardly any places available.
Opposition spokeswoman on childcare Sussan Ley said it was unacceptable parents were waiting for place for two to three years and in some cases had to quit their jobs or rely on grandparents.
"How many flashing lights does this government need before they actually do something?" she said.
Childcare Minister Kate Ellis said there were "outdated, nonsensical planning barriers" at the state and local government level preventing growth of new childcare services.
"When we asked the states to form a national taskforce to immediately take action to investigate and remove barriers to new child care centres, the Liberal States teamed up to block the proposal," she said in a statement.
"What we want the states to do is immediately put in place a plan to support child care growth, identify and release more land where it is needed, and remove barriers to support the development of new services."