Key Points:

A heavily pregnant 22-year-old woman was jailed for five years for burying a kitchen knife in her brother's chest where the 22cm blade snapped off.

Kama MacDonald had been found guilty at a Christchurch District Court jury trial last month on the charge of wounding with intent to cause grievous bodily harm.

The trial heard that early on New Year's Day, the brother and his partner, and then MacDonald arrived at the home they shared in the suburb of Phillipstown, after being out partying.

MacDonald walked in to find a domestic dispute under way.

Judge Jane Farish described what happened next as a tragedy for MacDonald and her brother.

She went into the bedroom where the argument was going on, and struck her brother on the arm with a beer bottle, which didn't break.

She then went to the kitchen, and took a large kitchen knife from a drawer before returning to the bedroom.

She stabbed her brother twice. The first wound was in the forearm, a deep cut that severed tendons and caused nerve damage.

The second wound was in the shoulder, penetrating the chest cavity and causing a lung to collapse. The blade broke off where it was embedded in his chest.

Her brother underwent surgery. He was expected to make a full recovery over time, with on-going treatment.

Defence counsel David Ruth asked for merciful treatment for MacDonald, bearing in mind the context of what was happening at the time of the incident.

Judge Farish said: "The pre-sentence report outlines the significant difficulties you have had in growing up. You are a high damaged young woman, Miss MacDonald."

She noted MacDonald had taken steps to sort her life out but a lot more work remained to be done. She had previous convictions for violence, including robbery in 2002.

But in the past two years she had been in a stable relationship, had taken steps to remove herself from the prison environment, had acknowledged her wrongdoing, was remorseful, and was willing to attend a restorative justice conference with her brother.

Jailing her for five years, Judge Farish said her release would depend on what steps she took to deal with issues of violence while in prison.