"As a mother, she owed her daughter a duty of care," Newcastle District Court Judge Tim Gartelmann said on Wednesday.

"She (the daughter) was in a home where she should have been safe and secure."

Judge Gartelmann said the mother's failure to seek medical help for the toddler who would have been in intense pain had been a substantial cause of her death.

"Her daughter may have lived if she had sought medical help at least earlier in the afternoon," the judge said when jailing the mother for five years with a minimum of two-and-a-half years.

Judge Gartelmann said the mother had expressed anguish over the toddler's death but she had never accepted responsibility and had shown no remorse.

The mother, 25, who did nothing for more than four hours as her daughter's condition deteriorated, claimed she just thought the dying girl had an infection.

She was found guilty in March by a jury of manslaughter due to criminal negligence.

Her partner, Timothy Whiteley was found guilty by a Supreme Court jury of murdering the toddler and jailed in February for 35 years with a minimum of 24 years.

The judge sentencing Whiteley said it appeared, given the blood on bedding and drawers, the first attack on the toddler occurred on the bed and she might have been violently thrown against the set of drawers but what had precisely taken place was unknown.

There seemed to be no motive for the attack except that Whiteley had earlier seen some suggestive text messages the mother had sent to his brother and he was stressed about losing his glasses.

Whiteley, 29, told police he initially believed the girl had fallen out of bed and hit her head.

The toddler died from multiple injuries, including bleeding to the brain, six broken ribs, a collapsed lung, lacerations to her liver and bleeding in her abdominal cavity.

Judge Gartelmann said on Wednesday the forensic pathologist who conducted the autopsy believed the toddler's injuries would have been obvious to the mother.

The judge said the toddler's rib fractures would have been "very painful" and touching her "would have caused intense pain".

He said the mother's claims that the toddler was giggling in the bath after the attack had to be rejected.

The toddler had been pale, floppy, lifeless with her eyes rolling back in her head and made bubbling sounds when she breathed but the mother did nothing.

Judge Gartelmann noted the mother later told police the first time she saw her daughter after the attack was "nothing like she had ever seen".

The crown case against Whiteley was that he had been the only adult in the toddler's bedroom when she was attacked in a house in the Hunter region on June 19, 2018.

Whiteley and the girl's mother had been the only adults inside the house with the toddler when there was a loud thud heard by a visitor sitting on the back verandah just before 12.20pm.

Whiteley carried the toddler from the bedroom area soon after in a clearly distressed state, unconscious and not responding but an ambulance was not called until 4.59pm.

The toddler was pronounced dead at 6.03pm at John Hunter Hospital.

Australian Associated Press