A South Canterbury woman who admitted having sex with a 15-year-old boy – and had a baby with him – has been sentenced to 10 months home detention.

The 34-year-old, who appeared for sentence before Judge Brian Callaghan in the Timaru District Court yesterday, was granted permanent name suppression. She showed no visible sign of emotion as she was sentenced to 10 months' home detention.

Following a pre-trial hearing last month, she pleaded guilty to a representative charge of sexual connection with a person under 16 years over a three-month period in 2008.

The relationship started after her husband took on a mentoring role with the boy, who had been getting into trouble. The boy started spending more time with the woman and became her chief confidant as she went through difficulties in her personal life. The pair embarked on a consensual sexual relationship.

In making submissions, Crown prosecutor Tim Gresson said a prison term with a starting point of 3 1/2years was appropriate. As a matter of principle there was no difference between sentencing a male or female offender, he said.

However, Mr Gresson conceded the court faced a conundrum over the issue of identification, as the woman had four children who could be called victims.

Defence counsel Wayne van Vuuren said he did not see any way the woman's children could be protected by any other means than name suppression for the woman and he submitted her children had already suffered adversely from media attention generated by the case.

Judge Callaghan said he saw no practical way of protecting the children if name suppression was not granted.

The woman's name, her estranged husband's name and occupation, and the names of the victim and his mother were suppressed.

"As much as I think you also need to be held accountable, I agree with your counsel that this is an unusual case," Judge Callaghan said.

In terms of sentencing Mr Gresson said intensive supervision, although recommended in a pre-sentence report, was unrealistic given the nature of the offending.

There were some troubling aspects about the woman's behaviour in that she was controlling and seemed to have an attraction to young teenage boys, he said.

"[The woman] not did seem to differentiate the 15-year-old victim from any other male she could have started a relationship with."

However, Mr van Vuuren directed his submissions to a sentence of community detention and intensive supervision.

A report prepared by Child, Youth and Family indicated the woman was not seen as a risk to either her own children or any other children.

Although the woman had arranged for her mother to take care of her children if she were jailed, imprisonment created a difficult proposition as that would involve uprooting the children, Mr van Vuuren said.

Judge Callaghan said the case was unique and unusual.

"I read this as being a situation where this relationship developed inappropriately but it happened as a result of circumstances.

"It should never have happened. She should have been the adult. She should have nipped this unhealthy relationship in the bud."

He considered 2 1/2years' imprisonment as an appropriate starting point for sentence. This was reduced to 24 months – making the woman eligible for home detention – after taking her lack of previous convictions and her guilty plea into account.

He sentenced the woman to 10 months' home detention and imposed standard and special post-detention conditions to apply for eight months.