Jacinda Ardern compared to Bernie Sanders on US Today show

Prime Minister Jacinda Ardern has been compared to US Democratic politician Bernie Sanders on popular United States breakfast show Today.

The feature story, which included a sit down interview with Ms Ardern in her home, then described New Zealand First as "very conservative".

"Ardern, former head of the young socialists teamed up with the 'very conservative' New Zealand First Party," the voice over said.

"It would be a little like Bernie Sanders teaming up with Ted Cruz."

During the interview, Ms Ardern also said she was "infuriated" when the Washington Post compared her immigration policy to that of US President Donald Trump in a tweet.

"That infuriated me. It infuriated me. We are a party who at the same time were campaigning to double our refugee quota. We are a nation built on immigration.  I'm only a third generation New Zealander," she said.

"The suggestion in any way that New Zealand wasn't an open outward facing country, the suggestion that I was leading something that was counter to that value, made me extremely angry."

The subject of Ms Ardern's pregnancy and the fact she is not married to partner Clarke Gayford were also focuses of the interview.

Ms Ardern said like many women, she will multitask her way through motherhood, and she said she is looking forward to pregnancy and power are not such an unusual combination.

"I'm looking forward to the day when we won't have news stories about that because it won't be nearly as unusual, but for now I accept that that's just the way it is," Ms Ardern said.

On the subject of marriage, Ms Ardern said her grandmother would probably like to see her married, but it's otherwise no big deal.

"We never have made as deliberate decision not to get married, but it's just something we haven't gotten around to. No one takes particular issue with this."