NEW Zealand Prime Minister Jacinda Ardern was admitted to hospital in Auckland for the birth of her first child on Thursday, according to a statement from her office.

The PM is four days past her due date, which was June 17.

Deputy Prime Minister Winston Peters was now acting prime minister and would run the country for the next six weeks while Ardern took maternity leave, the statement said.

Ms Ardern, 37, took office as New Zealand’s third female prime minister last year and announced in January that she was expecting a baby with her partner, TV fishing show presenter Clarke Gayford.

Ms Ardern, the leader of the New Zealand Labour Party, is the world’s youngest female head of government. She will also be the first to take maternity leave once her baby is born.

Rumours have been swirling about the sex of Ms Arder’s and Mr Gayford’s first child, but nothing has been confirmed.

Ms Ardern has twice had to quash speculation, most recently after Mr Gayford gave an interview to Radio New Zealand.

The excited father-to-be was asked about the couple’s future family addition, to which he responded “the reality is there, you know, that we’re going to have a child.”

He then went on to describe the infant as a “her”.

Ms Ardern and her partner know the sex of the child, but wanted to keep it out of the public eye.

The popular prime minister revealed she found about the bub after a fight with Mr Gayford, who hosts a fishing documentary show aptly named Fish of the Day.

“I was in Wellington, and Clarke [Gayford] was in Northland and he was doing his fishing show,” Ms Ardern told Sitting Room Only in May.

“I’d called him and we’d had a little bit of an argument about whether or not he was going to be able to get to Wellington for the announcement of who was going to form the Government.”

It was later that day she became aware of her pregnancy, and had to give her partner an awkward call back.

“Later on in the evening when I got the result of my test I thought, ‘oh my word, I’m going to have to call him back’,” she told Sitting Room Only.

“And I called him back, and he was kind of exasperated because I had just got off the phone to him, and he was surrounded by his whole film crew. And so he went into a toilet, so he was in a rented bach, in a toilet, when I told him.”

Ms Ardern has remained hard at work during the course of her pregnancy, and news of the child was celebrated worldwide when she announced she was due to give birth.

“There is a level of excitement because it is novel and because it’s really rare to see this globally. It’s quite a big moment,” Dr. Jennifer Curtin, a professor of politics and international relations at the University of Auckland told TIME.

“We had mania when she first became leader, ‘Jacinda Mania’.

“We will see the equivalent once the baby arrives.”

When the child arrives, Mr Gayford will become a full-time dad, while Ms Ardern continues to lead the country after her six weeks scheduled leave.