A woman will receive weekly ACC payments after discovering she was pregnant - an subsequently giving birth - eight years after a sterilisation procedure.

A woman who became pregnant eight years after a failed sterilisation operation will get weekly ACC payments because she is unable to work while she cares for her child, in a landmark decision.

The woman had the sterilisation procedure in 1998 and was told it had been successful. But, eight years later, she discovered she was 34-weeks pregnant and she gave birth to a son in June 2006.

Her lawyer, Dunedin-based Peter Sara, a specialist in accident compensation law and involved in thousands of ACC cases over more than 35 years, described the case as "exceptionally rare".

"This is the first decision that I'm aware of that the person not only has cover for pregnancy, but also for the consequences of having a child."

Previously pregnancy was viewed as a natural process and the idea of a "wrongful birth" was unacceptable from a public policy point of view.

"There may well have been cases similar to my client of failed sterilisations and they have just missed out."

Sara said his client was of low intelligence but had made a responsible decision in regards to her reproduction.

However, that operation resulted in an unwanted child "although she loves her child dearly".

Sara said his client became pregnant as a result of negligence meaning they were in a position to sue the hospital and doctor as the injury wasn't covered by ACC.

However before the case reached the High Court, a decision was released by the Supreme Court on a woman who became pregnant as a result of a failed sterilisation.

That decision awarded cover for the woman "for the physical effects of her pregnancy", which revived his client's ACC claim.

However ACC only offered compensation to his client for the time she was pregnant.

"I said hang on a minute the consequence of her pregnancy was that she has a child, you can't just ignore the fact she now has a child to look after."

The reserved judgment was "a bold move by the judge because it is breaking new ground".

ACC now had a month to appeal the decision, but Sara warned "that was risky because if they lose they have a HIgh Court precedent that is binding on ACC".

"Instead, when she was the subject of teasing for putting on weight, she became concerned that she had a tumour and sought treatment," the ruling states.

"She was accordingly shocked to find that she was 34 weeks pregnant, which by then was too late for an abortion even if it had been sought."

The woman sought weekly compensation from the ACC, but was only granted payments from May 2006 to July 2006, the period from when she was unable to work to when she was discharged from hospital after the birth.

She sought a review of the decision, arguing that she could not return to the job she held before having a child. The review was dismissed, so she appealed to the district court.

The woman has an intellectual impediment, according to the court ruling, and has been assessed as having low to average intelligence. When she became pregnant, she was working in a country hotel, which came with accommodation.

The judge ruled that other entitlements should be considered for the woman, "such as child care".

The judge permanently suppressed the woman's name.