It is understood the baby was about two months old at the time.
The alleged assault happened at a residential address in Pakuranga.
The baby's name and any identifying details are permanently suppressed.
The mother does not have name suppression but the Herald has chosen not to publish her name in case it leads to the child being publicly identified.
A source told the Herald that the baby was taken by ambulance to Middlemore Hospital, and then transferred to Starship Hospital.
She had extremely severe and life threatening head injuries.
Police and Oranga Tamariki were alerted and began an investigation into how the baby was harmed.
In February this year the was charged in Brisbane.
The process to extradite her then began.
In early August she was arrested and about a week later, extradited to Auckland.
Police could not comment on the case as it was before the courts.
The Herald understands the baby girl was extremely lucky to survive the injuries.
According to the woman's Facebook page she is from Auckland but attended high school in Australia.
Before her arrest she was a full-time mother living in Queensland.
Extradition is the official process of one country surrendering a suspected or convicted criminal from one state to another.
A country requesting extradition may rely on either an international treaty - such as the treaty between New Zealand and Australia - or on the domestic laws of the foreign nation.
The treaty between New Zealand and Australia is administered by police forces and prosecuting authorities on both sides of the Tasman.
Are you worried about the safety of a child?
If you have concerns about the immediate safety of a child, call 111.
Alternatively contact your local police station - click here for a list.
Or, contact Oranga Tamariki, Ministry for Children on 0508 326 459 for advice or click here to visit the agency's website for more information.
