Adam Ngahuru's attack on his partner while she held their baby on Christmas Day was described as domestic violence of the worst kind by the judge who jailed him.
He likened the assaults to the violence of the film Once Were Warriors.
The 20-year-old was jailed for two years four months at his sentencing in Christchurch District Court.
Ngahuru had admitted injuring with intent to injure, assault on a child, intentional damage, and threatening to kill charges.
Defence counsel Mark Callaghan handed a letter to the judge from Ngahuru saying it was informative and insightful.
He said Ngahuru was remorseful and had communicated his apologies to the victim, and he could not understand how he could have done what he did.
He accepted that prison was inevitable, Mr Callaghan said.
Judge Michael Crosbie said Ngahuru's partner was eight months pregnant and an argument started after Ngahuru had been drinking.
Their child was crying and Ngahuru took her to her bedroom. Her mother pushed him away and picked the baby up, and Ngahuru grabbed his partner by the throat and started strangling her.
Ngahuru's sister intervened, and his father pulled him away from her.
His partner ran, but Ngahuru went after her and punched her in the head and kicked her in the back as she sheltered the baby.
His father hit him with a cricket bat and held him while his partner got in a car.
Ngahuru got away, jumped on the bonnet, and smashed the windscreen. Both his partner and the baby got cuts and scratches.
His father used the bat again but Ngahuru shattered the driver's side window and punched his partner in the head and neck.
He was threatening to kill her during the assaults.
Judge Crosbie said it was domestic violence of the worst kind.
He said the partner's victim impact report said she was concerned as it all started because the baby was crying, and she had concern over the unborn child as well.
She still had issues of trust, and it had been terrifying for her, he said.
"This could be a subscript of Once were Warriors with Ngahuru's background, where he has learnt and is repeating this behaviour," Judge Crosbie said.
He said Ngahuru had a problem with alcohol and a history of violence.
He said it was a long drawn out attack and Ngahuru had many opportunities to retreat.
The child was vulnerable and the level of violence was significant, sustained and determined, he said.
He told Ngahuru it was up to him to get help while he was in prison, as with his past and his history he would continue to offend, without intervention.
He said it was only his age that saved him from a longer sentence.
He jailed him and ordered to pay $400 for the damage to the car.