The court heard the man had become irritated at how “loud” his baby was being and an argument subsequently erupted between him and his partner.
He spat in her face and began to throw items around the house and smash dishes.
The woman picked up the child and was in the process of leaving when the man punched her four times in the head.
As she shielded herself to avoid further punches, the man punched the baby in the head. He then took the baby and left.
The woman suffered a concussion and was taken to hospital by ambulance. When the baby was found some time later, it had visible signs of injury.
At the sentencing, Crown prosecutor Ally Tupuola said the defendant continued to deny aspects of the offending by insisting he pushed the victim rather than punched her.
This proved he lacked genuine remorse, Tupuola submitted.
But defence lawyer John Moroney argued his guilty plea was evidence of his remorse.
“What he did is of no credit to him whatsoever, but he has pleaded guilty to it, he’s accepted it,” Moroney said.
Judge John McDonald said family violence was rife in the community and men resorted far too often to using their fists against their partners.
“It is common knowledge police are called every six minutes to a family harm incident and almost all family harm coming before the courts involves a male assaulting a female,” Judge McDonald said.
“This started as something so minor as your baby being too loud. She could not defend herself because she was holding the baby, and the baby cannot defend itself at all.”
The judge rejected any community-based sentence options and, in a surprise to the defendant, sent him to prison for 15 months.