Funeral plans for a baby who died after being violently shaken are on hold until police receive the results of her post-mortem examination.

Six-month-old Serenity-Jay Scott-Dinnington died in Starship hospital on Thursday after her life support was switched off.

She was admitted to the paediatric intensive care unit on Tuesday night after suffering injuries that police say were non-accidental.

The little girl had been living with her mother, Chelsea Scott, 21, at a Ngaruawahia house. Miss Scott's brother Drew, 17, and fiance Mathew Ellery, 21, also lived at the house.

It is understood the two men were interviewed by police shortly after Serenity was taken to hospital. No arrests have yet been made and police investigating her death hope to have the post-mortem results today.

Miss Scott did not respond to messages over the weekend. She is believed to be staying with her father Rob Newman and Mr Ellery.

Mr Ellery's father, Shane Ellery, said last night funeral plans had yet to be completed. He said his son and Miss Scott were waiting for police to give them the go-ahead.

Shane Ellery has been told by police not to speak publicly about Serenity's death, or his son's role in her life.

But he said the baby's death was a "huge shock".

"I was there [at the couple's house in Ngaruawahia] about three days before it happened," he said. "Matt and Chelsea are with family ... He's coping. It's pretty upsetting for him and Chelsea."

Miss Scott's mother, Celeste, said the last few days had been "upsetting and very confusing".

She got a text from her daughter on Saturday but had yet to see her.

"She seems to be doing OK. None of us have any idea what's going on. I love my daughter and I miss her. I just want to give her a big, huge hug," she said.

Mrs Scott was angry no one had been arrested.

"Why, why, why has this happened? What the hell did this person do? Damn right I'm angry. I'm disgusted and I want to know who killed her. Someone is getting away with murder - because that's what it is to shake a baby."

Mrs Scott has serious health problems and said she had been "very down in the dumps and low", wishing she could trade places with her tiny granddaughter.

Police are urging anyone with information about who harmed Serenity to come forward.

"An innocent, 6-month-old baby is dead. She has died at the hands of another and it is everyone's responsibility to ensure that someone is held accountable for her death," said Detective Senior Sergeant Mark Greene.