The mother of a 17-month-old who died after her skull was fractured says it was not her who caused the fatal injury.

Sadie-Leigh Gardner died on 29 March 2019 in Starship Children's Hospital from blunt force head injuries.

The Tauranga toddler's death was the subject of two previous trials after her stepfather Adrian Clancy was charged with murder. He was found guilty and then acquitted by the Court of Appeal and found not guilty in a retrial.

Coroner Tracey Fitzgibbon is looking to establish how and when Sadie-Leigh sustained her injuries, and if they were accidental.

The toddler's mother, who has name suppression, told the inquest she did not cause the fatal injuries.

Clancy's lawyer Rob Stevens put to her that she was the one who caused the blow to Sadie-Leigh's head, even if unintentionally.

"I absolutely did not," she replied.

He asked her if she had had enough of Sadie-Leigh by the time she was put to bed. She had then had a coughing fit and struggled against some cough medicine, spitting it out.

"And that was what caused you to lose your temper with her, wasn't it?"

"Absolutely not," the mother replied.

"Was it the second time?" Stevens then asked.

"I didn't touch her. The second time I went in, I went in and visually looked at her," the woman replied.

He put to her that the reason she went back in before she left for an appointment was to check if Sadie-Leigh was okay after causing the injury earlier.

"I didn't make the injury, I didn't touch her," she responded.

The woman was also questioned about the way she spoke to Sadie-Leigh and if she was struggling as a parent. She admitted to raising her voice, but denied it being daily.

She did not recall swearing abuse or telling Sadie-Leigh to shut up and get away from her.

"I was a solo mum. At that time of my life, I would tell people she wasn't the easiest of children. I did struggle as a solo mum... I was tired as a solo mum.

And Sadie-Leigh had been sick, which she admitted made things harder.

"It's harder because they're grizzly, they don't want to sleep. A sick child demands more of your time."

Earlier, Sadie-Leigh's grandmother Stacey Maultsaid broke down in tears as she read her evidence.

She described being told by a doctor at Tauranga Hospital that Sadie-Leigh had brain injuries and was in a critical state.

"[Her daughter] just burst into tears and looked at me with absolute shock. She just said, what's happened to my baby. You could just see in her eyes there was just shock and sadness."

Maultsaid explained how they got to see her before she went in the helicopter to Starship Children's Hospital in Auckland.

"We both just freaked out and cried. Sadie was there with tubes in her mouth... I went up to Sadie and was giving her kisses, telling her she was going to be fine and that she was going to wake up."

She said her daughter also kissed Sadie-Leigh, telling her to wake up, that she would be okay, and that they would meet her in Auckland.

Sadie-Leigh was put into an induced coma and the pair drove to Auckland, arriving just after midnight.

"That's when the female doctor said I'm very sorry but there was nothing we can do for Sadie and that she was going to die. That's when she told us that Sadie had a massive brain injury or something like that," Maultsaid said.

"She said that surgery was not an option and nothing would help her. Then she told us Tauranga Hospital knew this but had sent Sadie up to them with a little bit of hope that they might have been able to do something for Sadie.

"[Her daughter] just looked at me and screamed. She started crying, started saying, not my baby."

Maultsaid had been watching Sadie-Leigh the morning of the fatal injury and said apart from a runny nose their was nothing about the toddler's health that concerned her.