It is understood the girl, from Kaitaia, died in Auckland's Starship Children's Hospital in early January, Fairfax reported.
A spokesman for the Coroner told the publication the "suspected self-inflicted death'' was also under investigation by the Coroner.
This week, clinical child and adolescent psychologist Dr Sarah Watson advised that parents listen if their child was in distress and to take their concerns seriously.
"Take the time to really listen...[and for harmful thoughts or behaviour] that arise out of distress - you want to be talking about the reasons for the distress and what to do about it.
"Help them find hope,'' she said.
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• Samaritans: 0800 726 666
• If it is an emergency and you feel like you or someone else is at risk, call 111