Karl Barnes told his heavily pregnant partner he would smash her over in front of officers if she called police.
Barnes had woken up in a bad mood on January 4 and began screaming at his partner, who was 37 weeks pregnant.
The frightened woman took her two young children into the lounge before trying to remove a key to her house from his keyring.
Barnes responded by grabbing her by the wrists and started shaking her.
Today Barnes appeared before Judge Ian Carter in the Whanganui District Court to be sentenced on two charges of assaulting a person in a family relationship, two of speaking threateningly and one of threatening behaviour likely to cause violence.
Barnes, who was on bail for previously assaulting the victim, also told her he would slash her car tyres and smash up her house before police could get there.
He also threatened to "smash her over" in front of the police when they arrived.
Judge Carter said the threats had significantly affected the victim who was distraught and clearly upset.
"She believed at the time that you were capable of carrying out your threats."
Earlier, in August last year, the couple, who had been in a relationship for about six months and were expecting their first child, had a verbal argument that escalated to violence.
When she tried to leave, Barnes threw a mattress at her pinning her against the wall.
After the woman broke free Barnes grabbed her from behind, pushed her into the hall causing her to fall stomach-first onto wooden furniture, which caused considerable pain.
She told Barnes she would call police but he responded "I could do a lot of damage in the five minutes before the cops get here".
The victim was eventually able to leave the address.
Defence lawyer Richard Leith said Barnes accepted he had lost control and acknowledged he needed to get control of his anger.
"He does not want to be like this, he wants to get help."
Leith urged the judge to impose a sentence of home detention rather than imprisonment.
Despite Barnes' victim taking a protection order out against him, she wanted to be able to have contact with him, he said.
Police prosecutor Sergeant Graham Hoskin supported a sentence of home detention.
Judge Carter said Barnes had long-standing substance abuse issues, which had significantly contributed to his offending.
He acknowledged the home detention address was a pro-social environment with a pro-social person who was "prepared to support you to address the underlying issues".