A five-year-old girl watched as her mother took repeated strikes to the head before being taken to hospital with what could have been "catastrophic damage" to her brain.
Robert Paul Strickland, 48, had no violent convictions before pleading guilty to assault with intent to injure at the Whanganui District Court on Tuesday.
Police prosecutor Sergeant Drew Morrison said on March 13 at about 8pm, Strickland was arguing with his partner over money when he "lashed out" and began punching her in the head.
"The victim received bruising to her face, a cut lip, scratching to her neck...and was treated by an ambulance and taken to hospital," Mr Morrison told the court.
Mr Morrison said the victim's five-year-old daughter witnessed the event.