The mother of a baby killed by her partner says he has stolen the joy of motherhood from her.

Daniel Wallis has been jailed for three-and-a-quarter years for the manslaughter of his five-month old-daughter Hope McFall-Schultz.

Hope was born three months premature in August 2021. In January last year, she suffered critical injuries while alone with Wallis at home in Invercargill and died four days later.

Wallis initially claimed the baby had wriggled off his knee and struck her head on a feeding bottle on the floor. He told police this caused her nose to bleed and the sight of blood caused him to vomit, during which he accidentally struck Hope's head on a benchtop.

A post-mortem proved that series of events false. Wallis then admitted to hitting the infant three times in the head with an open hand.

In a victim impact statement read by Detective Sergeant Mark McCloy, Hope's mother Brittany McFall-Schultz detailed how Hope's death had affected her life.

"Everything has changed for me. I don't see or experience life the same anymore. I am angry," the statement said.

"I blamed myself and became suicidal. Past trauma resurfaced and undid all the progress I had been making.

"I don't sleep properly. My family life has been affected. I have lost all my family relations as I can't be around kids like my nieces or nephews anymore because they remind me of Hope.

"I have been homeless and I have lost everything because I could not go back to our house after this happened. I have been in and out of the police cells because of my anger.

"The thought of trying to get on with my life without Hope seems impossible. I don't see life the same anymore. I am scared to restart my life. I don't trust anyone and I don't know if I ever will again.

"Having Hope was the greatest happiness I have ever experienced in my life. Hope fought so hard to be here, the endless days and nights we spent in neonatal. You have taken the joy and ripped motherhood away from me.

"Hope was a mini-me and a reincarnation of my mum. I miss her cheeky grins and big smiles.

"You are not the man I thought you were. Everything was a lie. I will regret being with you for the rest of my life, but I will never regret Hope. She was my world."

Wallis spent much of the sentence with his head bowed and tears in his eyes. Justice Melanie Harland said he had difficulties in life, though nothing justified what he did in January last year.

Hope had spent several weeks in hospital after being born prematurely and vulnerable.

She had only been discharged from hospital about a month before her death.

On 19 January 2022, a doctor examined the child and told her parents she was progressing well.

Two days later, McFall-Schultz fed her baby and went to visit some friends.

"There is a suggestion you were not happy about this given that for you it was the end of a long week of 12-hour days," Justice Harland said.

"You described feeling under pressure at the time because you were exhausted, financially stressed and having relationship difficulties."

The judge said before that night there had been no suggestion Hope was at risk of violence from Wallis.

"A neonatal homecare nurse described you as caring and loving towards your daughter. I accept you were feeling overwhelmed, stressed and tired at the time and that this might explain your sudden loss of control - but as your lawyer correctly noted, it does not mitigate the seriousness of your offending."

It was hard to imagine a more vulnerable victim, the judge said.

"You were her father and it was your job to care for and protect your daughter - you did not do so, and therefore your offending against her amounted to a gross breach of trust."

The judge took a starting point of five-and-a-half-years' imprisonment, but accepted there were mitigating circumstances, including an early guilty plea to the reduced charge, an admission of his violence and remorse.

"I need to acknowledge that you too have been profoundly affected by what you did ... I also accept that your lack of previous convictions and very real remorse, which I consider is over and above that reflected in your guilty plea, and your relative youth require further discounts."

Reproduced with permission