'I predict we will one day' - marriage on the cards for PM

The world is reacting to the news Prime Minister Jacinda Ardern is having a baby.

"Clarke and I are really excited that in June our team will expand from two to three," she said on Facebook.

In a media release, Ms Ardern said she and partner Gayford weren't sure "if it would happen for us, which has made this news unexpected but exciting".

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4:30PM - "I predict we will one day" - marriage on the cards for PM

Speaking to Lloyd Burr on RadioLIVE this afternoon Ms Ardern admitted while marriage was not exactly on the forefront of her mind she thinks she will one day marry her partner Clarke Gayford. 

"We are a really open and tolerant society in New Zealand…  neither of us have a particular stance on marriage," she said

"I predict we will one day it just we happen to have done things in reverse a little bit, but that happens in life sometimes too."

2:50pm- "I didn't know what it was like to be Prime Minister without being nauseous."

In an interview with Wendyl Nissen on RadioLIVE, Jacinda Ardern said she first felt the effects of morning sickness on the day she was sworn in as Prime Minister.

"It fully kicked in the day that I was sworn in as Prime Minister," she said.

"I didn't know what it was like to be Prime Minister without being nauseous."

The Prime Minister says she was aware she got off lightly, saying she has a friend who suffered from far worse morning sickness, and her mother suffered throughout her entire pregnancy.

Around the time of the birth, Ms Ardern's parents will finish their posting in Niue where her father is the High Commissioner. Her sister is also moving back to New Zealand from London with her family.

Ms Ardern expects her partner Clarke Gayford will receive a lot of help from his family, including his two sisters who have five young children between them.

She said that once her six week parental leave is up, she can look forward to a more family-friendly parliament to return to, with Mr Gayford by her side looking after their baby.

"The speaker has made a really conscious effort to try and make sure that Parliament is a more family-friendly work environment," she said.

"You know, Clarke will be travelling with me and also being at home, so yeah I feel lucky.

"I'm under no illusion that it will be tough, but we've got a lot of support."

1:10pm - 'Ours is a novel coalition' - Winston Peters

Winston Peters has congratulated Ms Ardern on her pregnancy.

"On behalf of my New Zealand First colleagues we wish the Prime Minister and her partner every joy during the next several months as they adapt to a new challenge," The NZ First leader said in a media release.

"Ours is a novel coalition in many respects and the Prime Minister’s announcement only reinforces its unique qualities.

"We are committed to supporting the Prime Minister during the months ahead to continue to provide a good and stable government.

"We understand that no matter what level a person operates on family life is important."

When contacted by Newshub, Mr Peters' office said he would not be making appearances today, as "it's the Prime Minister's day".

12:50pm - Ardern acknowledges pregnancy timing

Jacinda Ardern has acknowledged the timing of her pregnancy.

She found out on October 13, during coalition talks with Winston Peters.

"People will probably look at the timing," she said, before emphasising it was a surprise for her too.

"We didn't know for sure if it would ever be a reality for us."

Ms Ardern said she didn't tell anyone "around the table", but it played on her mind during the negotiations.

"I'm only human".

She told Mr Peters before making the public announcement, adding morning sickness made it difficult to keep a secret.

12:45pm - Clarke Gayford on finding out Ardern is pregnant

Clarke Gayford was in the bathroom when he received news of partner Jacinda Ardern's pregnancy.

He'd slipped away from filming his fishing show to take her Facebook video call.

It was "quite the reveal", he said.

"Big shock."

12:40pm - 'I'm not the first woman to multitask' - Ardern

Jacinda Ardern has acknowledged other women who have juggled pregnancy with work.

"I am not the first woman to multitask… I sympathise with all women who have experienced morning sickness.

"I've had a few messages of support already form women who have done things like have twins and juggle responsibility.

"There are plenty of women who carved a path… to be able to make it possible."

12:35pm - " I take very seriously the role of becoming a mum" - Ardern

Jacinda Ardern is live in a press conference.

"I take very seriously the role of becoming a mum… but equally take seriously the rold of being Prime Minister of New Zealand."

After giving birth partner Clarke Gayford will with her "a lot".

"We're both privileged and lucky Clarke will be able to do that job full time.

"New Zealand will help us raise New Zealand's first child."

The couple already know the gender but have decided to keep it a secret.

"We have a wage on who's going to blow it."

When Ms Ardern found out on October 13, Mr Gayford was away filming a fishing show.

"I found out our surprise and I, as I tend to share all our big news, Facebooked [him].

"I used the video function so we could speak face-to-face."

12:29pm - Newshub breaks regular programming for Jacinda Ardern press conference

Newshub has broken regular programming on Three for a press conference with Jacinda Ardern.

The livestream can also be found on Newshub's website and Facebook page.

12:22pm - 'An incredible privilege' - Bill English

Former Prime Minister Bill English has called being a parent "an incredible privilege".

"A new child will bring real joy to their lives."

Mr English has six children with his wife, Mary.

12:15pm - As an elected official, Ardern not eligible for paid parental leave

Jacinda Ardern is not eligible for paid parental leave.

Technically, as an elected official, she is not an employee so does not fall under the employment law provisions.

She will, however, take six weeks off after giving birth.

A Bill increasing paid parental leave to 22 weeks from July next year and to 26 weeks from July 2020 passed late last year.

The scheme kicks in on July 1, 2018.

12:10pm - Well wishes from across the ditch

Australian Prime Minister Malcolm Turnbull has called the pregnancy "wonderful news".

"When we spoke this morning you sounded more excited than you did when you won the election!

"Lots of love and best wishes from me and Lucy and all of us across the ditch."

12:08pm - David Seymour sets politics aside

David Seymour has set politics aside to congratulate Jacinda Ardern.

"Of course we are political opponents, but congratulations to @jacindaardern on her wonderful news," he said.

12:05pm - Minister for Women posts heartwarming tweet

The Minister for Women Julie Anne Genter has made a heartwarming post on Twitter.

"So excited or you," she said, alongside a photo of the pair hugging.

"What amazing timing. We'll all be on hand to help!"

12:00pm - 'This is wonderful news' - James Shaw.

Green Party co-leader James Shaw has called Jacinda's pregnancy "wonderful news… significant for many women, in particular".

"That a woman can be the Prime Minister of New Zealand and choose to have a family while in office says a lot about the kind of country we are and that we can be – modern, progressive, inclusive, and equal."

11:50am - Ardern won't be the first PM to give birth

Jacinda Ardern won't be the first Prime Minister to have a baby.

Nearly 30 years ago Pakistan Prime Minister Benazir Bhutto gave birth to her second child while in power.

11:40am - 'Every woman should have the choice' - Helen Clark

Former Prime Minister Helen Clark has congratulated the couple.

"A super busy year coming up & much to look forward to," Ms Clark said on Twitter.

"Every woman should have the choice of combining family & career."

11:35am - Politicians react

More well wishes are flooding in from politicians.

11:30am - Clarke Gayford to become a stay-at-home dad

Jacinda Ardern's partner Clarke Gayford will become a stay-at-home dad.

Ms Ardern will take six weeks off after giving birth, with deputy Prime Minister Winston Peters filling in.

11:25am - News breaks overseas

Foreign media is breaking the news.

Media in the UK, India, Australia and the United States have posted articles on their websites.

Ms Ardern received international attention throughout her campaign for both her age and her quick success.

11:15am - Bill English offers his congratulations

"Mary and I wish them all the best for the impending arrival," the former Prime Minister said on Twitter.

Mr English and his wife Mary have six kids.

10:51am - News breaks of pregnancy

Jacinda Ardern has announced she is pregnant.