New Zealand Prime Minister Jacinda Ardern pregnant with first child

New Zealand Prime Minister Jacinda Ardern has announced she is pregnant.

Posting on her Facebook page, Ardern said she and her partner Clarke Gayford were expecting their first child by the middle of the year.

"And we thought 2017 was a big year! Clarke and I are really excited that in June our team will expand from two to three, and that we'll be joining the many parents out there who wear two hats," she wrote.

"I'll be Prime Minister AND a mum, and Clarke will be 'first man of fishing' and stay at home dad.

New Zealand PM Jacinda Ardern has announced she's expecting her first child in June.Credit: Mick Tsikas

"I think it's fair to say that this will be a wee one that a village will raise, but we couldn't be more excited."

Ardern is New Zealand's third female prime minister, and has been in the top job since October 2017.

She said she and Gayford knew of her pregnancy on October 13, but did not share their news until her pregnancy was further along.

Ardern, 37, said the news was extra special for the couple, as they were not sure they would be able to have children without help.

Gayford and Ardern found out they were expecting in October.Credit: DAVID WHITE

"We're both really happy. We wanted a family but weren't sure it would happen for us, which has made this news unexpected but exciting," she said.

Gayford is a television and radio presenter, who hosted a fishing show on local television called Fish of the Day. Ardern said her partner, who is also a keen surfer, was just as excited as she was about the news.

Ardern said she and Gayford "wanted a family but weren't sure it would happen for us".Credit: Lawrence Smith/Stuff

"Clarke and I have always been clear we wanted to be parents but had been told we would need help for that to happen.

"That's made this news a fantastic surprise."

In a media conference outside her house in Auckland, Ardern said she was in the middle of leadership negotiations when she found out, and Gayford was away filming for his fishing show, so she video-called him through Facebook.

He took the call in a bathroom, she said - "but not the toilet", she clarified.

As for concerns about her ability to run the country and be a mother, Ardern said she was far from the first person to work and have a baby.

"I am by no means the first woman to multitask," she said.

"In terms of being a woman in politics, there are plenty of women who carved a path and incrementally led the way to be able to make it possible for people to look upon my time in leadership and think, yes, I can do the job and be a mother."

In August, the day after she became leader of New Zealand's Labour Party, Ardern was questioned about her baby plans on radio - comments she labelled "totally unacceptable" in this day and age.

AM Show panellist Mark Richardson had said: "If you are the employer of a company you need to know that type of thing from the woman you are employing ... the question is, is it OK for a PM to take maternity leave while in office?"

Arden hit back.

"For other women, it is totally unacceptable in 2017 to say that women should have to answer that question in the workplace. That is unacceptable in 2017. It is the woman's decision about when they choose to have children," she said.

"It should not predetermine whether or not they get the job."

Ardern and Gayford said they already knew the baby's gender but planned to keep it a secret.

"There is very little about our life we get to keep secret," she said.

However, the pair had a wager on who would let the news slip first.

Ardern said she would take six weeks' leave after the birth, and felt privileged her partner could stay at home to look after their child.

"Knowing that so many parents juggle the care of their new babies, we consider ourselves to be very lucky."

She said she met Deputy Prime Minister Winston Peters on Thursday and asked him to be acting prime minister while she is on maternity leave.

"As is the case when I am overseas, Mr Peters will act as prime minister, working with my office while staying in touch with me. I fully intend to be contactable and available throughout the six-week period when needed," she said.

"Mr Peters and I have a great relationship, and I know that together we'll make this period work. I will make arrangements for appropriate ministers to act in my other portfolios over the six weeks I am away from Parliament.

"At the end of my leave I will resume all prime ministerial duties."

Australia's Prime Minister Malcolm Turnbull was quick to congratulate his Kiwi counterpart, noting that when they spoke she sounded more excited about the pregnancy news than when she won the election.

with Stuff