The mother of a baby boy who died from a head injury recorded her then-boyfriend in the days before the child died in a Melbourne hospital.

Jesse Vinaccia, 25, is standing trial in the Supreme Court of Victoria, charged with the child homicide of his girlfriend’s 17-week-old baby, Kaleb Baylis-Clarke, in January 2016.

The Crown alleges Vinaccia either shook or manhandled the baby when his new girlfriend went to work.

Kaleb died in hospital from severe bleeding of the brain on January 30, a week after Vinaccia found the child unresponsive in his cot.

Vinaccia had moved in with the young mother and her newborn only a few weeks before the alleged shaking or manhandling incident.

On Friday, the court was played a recording between the baby’s mother Erin and Vinaccia on January 26, while Kaleb was on life support.

During the recording, Ms Baylis-Clark can be heard quizzing Vinaccia about the events on January 23, telling him: “I don’t want you to think I’m not on your side” and “accidents happen”.

She encouraged Vinaccia to tell her what happened, so the doctors could treat him accordingly.

But Vinaccia denied giving Kaleb his head injury.

“I went back into his room to change his nappy and he wasn’t breathing,” Vinaccia can be heard telling his then-girlfriend.

Ms Baylis-Clark told the court on Friday that on January 30, Kaleb’s life support was turned off after doctors were unable to detect brain activity, and her relationship with Vinaccia ended.

She said that earlier that month, she noticed Kaleb’s head getting bigger, and there was an egg-shaped lump on his fontanelle – the space between the skull’s major bones which fills and hardens as a child grows.

During that previous hospital admission, doctors who performed an ultrasound and MRI and found a build-up of fluid in Kaleb’s head.

However, he was allowed to return home a few days later as he seemed to be improving, Ms Baylis-Clark, now 24, said.

She will continue her testimony on Monday.

-AAP