Supreme Court judge Margaret Wilson ordered the termination after accepting medical advice that the continuation of the pregnancy posed serious dangers to the mental health and wellbeing of the girl.Her intellectual age was deemed by an obstetrician to be that of a six-year-old.
Queensland Health last night declined to comment on whether the abortion - using the labour-inducing drug misoprostol - had already been performed after the secret hearing last week.
Justice Wilson made her decision within hours of the urgent hearing, but it was not publicly released until Friday.
Police are investigating the father of the unborn child. His location is not known, but he is thought to be living in Queensland. Police and Queensland Health were unable to comment on whether the father was an adult or also a minor.
It is not the first time the judiciary has ordered an abortion in Australia, but it is believed to be the first time in Queensland that a decision of this type has been made public.
The girl's parents - who are divorced - had previously consented to the abortion and evidence was also given to the court that the expectant mother had told carers at a public hospital that she wanted to terminate the pregnancy.
Queensland Health applied to the Supreme Court to use its parens patriae powers to override the rights of the child's parents even though they had consented to the termination.
It is understood one of the reasons was because the mother of the unnamed child, "B", works in a remote community in NSW and the necessary documents could not be signed within the urgent time frame.
The child normally lives with her mother, who moved interstate a month ago, leaving her in the care of her father and grandmother.
In her written decision, Justice Wilson cited previous cases in which a court had ruled that parents could not validly consent to the sterilisation of an intellectually disabled girl because of the risks of making the wrong decision.
In Queensland, it is illegal for doctors to carry out an abortion unless it is performed to save a woman's life. It is also believed to be the first time that a Queensland court has ordered the use of the drug misoprostol in a sanctioned abortion.
Justice Wilson said the drug was the safer option given the girl's advanced pregnancy. "The risk of using alternative procedures to terminate B's pregnancy are far higher," she said.