New Zealand leader Jacinda Arden pregnant

Getty Images | Hagen Hopkins

Prime Minister-designate Jacinda Ardern and NZ First leader Winston Peters shake hands during a coalition agreement signing.

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

The Labour leader, who was elected in October after she formed a center-left coalition, revealed Friday that the news of the surprise pregnancy came just six days before she became prime minister.

“It was a week before (Deputy Prime Minister) Winston Peters made his decision about how to form a coalition government. It’s been a long time to carry that secret,” she said.

At 37, Ardern is New Zealand’s youngest prime minister since 1856. She is now set to be only the second elected world leader to give birth while in office.

In 1990, Benazir Bhutto gave birth to a daughter while serving as Pakistan’s prime minister.

Ardern is to take a six-week maternity leave, during which Peters will act as New Zealand’s leader. She said her husband is to be a “stay at home” dad.

In July last year, Ardern had been leader of the opposition for just one day when she was asked by a talk show host if she had to make a choice between children and a career.

Ardern gained an instant boost to her campaign when she answered that such a question was “totally unacceptable in 2017.”