Parents in Tasmania could choose whether to include their baby's sex on a birth certificate under transgender rights reforms passed by the state's lower house.
The legislation, put forward by the Labor opposition and the Greens, was voted through on Tuesday night after lengthy debate.
The bill also allows people aged 16 years or older to change the sex listed on their birth certificate by filling out a statutory declaration.
Transforming Tasmania, a transgender and gender-diverse rights group, lauded the changes.
"I applaud the Tasmanian lower house for providing greater equity, dignity and hope for transgender, gender diverse and intersex Tasmanians," spokesperson Roen Meijers said.
Labor's justice spokeswoman, Ella Haddad, said it was a great outcome on the back of the marriage equality vote that won't diminish the rights of others.
The changes were passed by the casting vote of rogue Liberal Speaker Sue Hickey, who voted against her party and with Labor and the Greens.
Liberal Attorney-General Elise Archer believes the amendments are deeply flawed.
"This amended bill contains legally untested, unconsulted and highly problematic changes that we could not support," she said in a statement.
An amendment to Tasmania's anti-discrimination laws, designed to ensure the correct use of transgender people's names and honorifics, was also passed.
The changes were attached to a bill introduced by the government that would stop people who transition genders from being forced to divorce, bringing state laws in line with federal legislation.
The government had wanted the amendments referred to the Tasmania Law Reform Institute.
"These changes will make people, who we should all care about, feel happier, safer and more included," Greens leader Cassy O'Connor told parliament.
The bill must still pass Tasmania's upper house of mostly independents before becoming law.
