Spain's first female defense minister was cast into the media spotlight when she took office in 2008, seven months into her pregnancy.
"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", Ardern explained, the New Zealand Herald reports.
Having found herself in the midst of tough coalition negotiations after a closely fought election, Jacinda Ardern was facing far more than her political colleagues could have guessed.
Ms Ardern said she was already receiving plenty of advice from Labour MPs on her pregnancy and bringing up the child.
Ardern revealed on Friday that she had unexpectedly found out she was pregnant on October 13, just six days before she was propelled into the country's top job when New Zealand First Party leader Peters announced he was siding with Labour in post-election negotiations.
"We thought 2017 was a big year!"
The Prime Minister's partner Clarke Gayford is one of those in attendance.
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New Zealand has long held a progressive reputation, having been the first country to given women the right to vote in 1893.
Two of New Zealand's former prime ministers were among the first to offer congratulations. Ardern, who identifies as a feminist, went on to explain that she'll be wearing "two hats" after she has her child, serving as both "Prime Minister AND a mum".
She said she was now planning on the birth being at Auckland Hospital.
"I am not the first woman to multi-task". Her third child, Prince Andrew, was born in 1960, and the fourth, Prince Edward, in 1964.
"It was a week before (Deputy Prime Minister) Winston Peters made his decision about how to form a coalition government".
However, she assured those with concerns that, "I take my role as PM incredibly seriously".
One of the tech world's most influential women, the chief executive of the streaming video service YouTube announced she was pregnant with her fifth baby a few months after she took on the job in 2014.