WARNING: this story may be upsetting to some people.

Authorities are working to establish whether a baby found dead at Auckland's Middlemore Hospital was stillborn or died after it was concealed in a bin soon after birth.

The newborn was found within the hospital on Wednesday morning.

Police are limited in what they can say about the death as their investigation is in its early stages.

The Herald has been told the infant was found in a toilet rubbish bin.

It is understood the mother had been taken to hospital by family members shortly before the baby was born.

It is unclear if they knew about her pregnancy.

A post mortem was carried out yesterday in a bid to find out if the baby was stillborn or died after birth.

Detective Senior Sergeant Mike Hayward said the death was still "unexplained" and it might be some time before there were any conclusive answers.

He said the post mortem had been completed but "further testing" needed to be conducted before the baby's cause of death could be confirmed.

Police would not be drawn on the circumstances of the baby's family.

"Police are working closely with the mother of the child and her family at this extremely difficult time for them," Hayward said.

"This investigation is very sensitive in nature and police are not in a position to provide any further details."

He said "a number" of inquiries were underway.

WHERE TO GET HELP:

If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.

OR IF YOU NEED TO TALK TO SOMEONE ELSE:

• LIFELINE: 0800 543 354 or 09 5222 999 within Auckland (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633 ,free text 234 or email [email protected] or online chat.
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757
• SAMARITANS – 0800 726 666.