New Zealand has legalised abortion, removing the practice from the Crimes Act and liberalising access to abortion services.

The final vote on the bill passed 68 to 51, it will now head to the Governor-General for the royal assent before becoming law.

The new law liberalises abortion rules, treating the practice as a health matter rather than a criminal one.

People will now be able to access abortions from a health practitioner in the first 20 weeks of pregnancy.

After 20 weeks, people will still be able to access abortions, but only after proving to one health practitioner that an abortion is "clinically appropriate," with regard to their physical and mental health and wellbeing. That practitioner must then consult a second practitioner before proceeding.

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This liberalises the current law.

While abortion currently sits in the Crimes Act, abortions are still carried out by exploiting a loophole.

But critics had argued this didn't reflect best medical practice, delaying the procedure unnecessarily by forcing people to get the approval of two medical practitioners before being allowed an abortion, no matter the length of term.

This point was made by Green MP Jan Logie who argued the biggest change the current law would bring about would be to enable abortions that would probably happen anyway, be conducted according to best medical practice.

"Abortions that happen anyway wil happen earlier," Logie said.

While the law brings abortion laws closer to best clinical practice, it still falls short of the model the Law Commission said was preferred by most health practitioners and professional bodies.

Health practitioners and professional bodies were "almost unanimous" in their support of a law that would have removed any statutory test before getting an abortion.

Monique Ford/STUFF Andrew little opens the abortion debate in parliament

Politicians nevertheless opted for a compromise option, without a statutory test before 20 weeks.

The bill was in the name of Justice Minister Andrew Little, who said it "confirms the right of a woman to continue with her pregnancy or not".

Although the bill was a Government bill, it was treated as a conscience vote meaning MPs didn't vote along party lines.

It has faced a small but well organised opposition in its journey through Parliament, passing its first reading 94 votes to 23 and its second reading 81 votes to 39.

The margin narrowed between second and third readings when most NZ First MPs switched their votes.

The bill's final reading was marked by several emotional speeches.

Labour's Kieran McAnulty told the House that he had been adopted.

"If I were conceived today, I would probably be aborted," he said, saying that his personal story and Catholic faith meant many would assume him to be against the bill.

But he nevertheless voted in favour.

"Who am I to push my personal views and my circumstances onto a woman?" he said.

National MP Agnes Loheni spoke against the bill, saying that supporters a "radical liberalisation" of the existing abortion regime.

One matter that continued to be a source of contention was the issue of safe areas around abortion clinics. Safe areas would have made it illegal to protest around certain clinics, but they were removed from the bill during the committee of the whole house stage.

Green co-leader Marama Davidson attempted to revisit this part of the bill by sending it back to the committee stage for another vote, but the attempt failed.

National's Amy Adams said she believed in safe areas and described the protests outside abortion clinics as "psychological abuse and torture".

Earlier on Wednesday NZ First MP Darroch Ball had tried to put the law to a referendum, but this also failed.

The party tried a similar tactic on David Seymour's End of Life Choice legislation. NZ First managed to amend that law to include referendum after threatening to pull support if their amendment failed.

It had been assumed that after failing to secure a referendum on abortion law reform, the party would likewise pull its support.

Instead, it split, with MPs Tracey Martin and Jenny Marcroft voting in favour. The party's other seven MPs, all male, voted against the bill.

Martin had been a key figure in the reform process. She had negotiated she shape of the draft will with Little.

The last speech went to National's Amy Adams, who will retire from Parliament at the next election

In what is likely to be one of the last major speeches in her political career, Adams said her conscience would be "absolutely clear" that she had done [her] bit to stand up for the women of New Zealand".

She said the current bill did not work and was outdated — when it was passed "there were only four women members, but there were more men called William in this house than there were women MPs".

"I am very proud that in my last few months in this house that I can put that right for a number of women today," she said.