Clarke and I are really excited that in June our team will expand from two to three, and that well be joining the many parents out there who wear two hats, the 37-year-old wrote.
Ill be prime minister and a mum, and Clarke will be first man of fishing and stay at home dad. I think its fair to say that this will be a wee one that a village will raise, but we couldnt be more excited.
In 1990, Pakistans then prime minister, Benazir Bhutto, gave birth to a daughter, in what was said to be a first for an elected world leader.
The deputy prime minister, Winston Peters, will take over to allow Ardern to take six weeks of maternity leave after the baby is born. In a statement Ardern said she intended to be fully contactable during her period of maternity leave.
At the end of her leave she intended to resume all prime ministerial duties, she said.
The Green party leader, James Shaw, congratulated the prime minister and Gayford.
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, Shaw said.
For that reason I know this announcement will be significant for many women, in particular, and that all New Zealanders will share in the prime ministers joy today.
Ardern said her pregnancy had been confirmed on 13 October, meaning her child would have been conceived during one of the closest election campaigns New Zealand has seen, with Ardern finding out the news six days before being confirmed as prime minister.
The former New Zealand prime minister Jenny Shipley said it was brilliant news.
Its a wonderful choice of our outstanding young woman leader who is also going to choose to be a parent, Shipley told RNZ. It will bring special insight I suspect in her work and joy to her family.
Another former prime minister, Helen Clark, tweeted her best wishes.
Ardern spoke to Australias prime minister, Malcolm Turnbull on Friday morning to share the news, as well as holding a phone conference with her ministers and other key government figures.
Ardern said she and her partner knew the sex of the baby but would be keeping the secret to themselves.
Asked by a reporter how she managed to set up a government at the same time as having morning sickness, Ardern replied Its what ladies do, revealing that no-one involved in the coalition talks picked up on her state.
Gayford, a television presenter on a TV fishing show, would become a stay-at-home father, and accompany Ardern as much as possible with the new baby when she went back to work to allow the prime minister to spend time with her child.
Were going to make this work and New Zealand is going to help us raise our first child, Ardern said.
She told her partner Gayford about the pregnancy using Facebook messenger while he was away filming. The news came as complete surprise to both, as they had been told they would need help conceiving a baby.
Ardern said before being elected Labour leader in August last year she and Gayford had started taking steps to have a family but those efforts stopped once she was promoted to leader.
Morning sickness had made keeping the secret a little tricky, but otherwise so far the pregnancy symptoms had not been too bad and she did not predict her government having to adapt too much to her baby except for the cabinet cars installing baby seats.
Ardern noted that the Speaker, Trevor Mallard, had already encouraged a family-friendly environment in parliament, and had repeatedly been photographed holding MPs babies while they were engaged in debate.
Lots of people juggle a lot of things in their personal and private lives, and Im not unusual in that. Plenty of women have multitasked before me, and I want to acknowledge that.
Gayford said he was looking forward to diving into the great unknown of being a dad, and was getting lots of advice from his female friends and sisters.
Initially it will be really important that Jacinda gets as much time as possible [with the baby] so I am going to try and be as flexible as possible, and close, so shes across everything as much as possible.
A reporter at Arderns media conference asked if the couple planned on getting married, to which Gayford responded, Wow, I like the idea that were doing everything in reverse.
In early August, six hours after being elected to lead the Labour party, Ardern was grilled about her baby plans repeatedly by New Zealand media.