Hodan Yasin, 21, was transferred to Brisbane from the Pacific island nation on Tuesday morning after suffering critical injuries from self-inflicted burns a day earlier.
Immigration Minister Peter Dutton told parliament on Tuesday afternoon Ms Yasin's condition was unlikely to improve.
"We can of course hope for the best possible outcome, but it is a dire situation," he said.
Ms Yasin's actions came less than a week after Iranian man Omid Masoumali, 23, also set himself alight on Nauru, before dying in Royal Brisbane Hospital on Friday.
The acts of self-immolation have prompted advocacy groups and the United Nations' refugee agency to criticise the government's offshore detention policy, which they argue causes refugees to give up hope.
