Jacinda Ardern was elected as the new leader of New Zealand's Labour opposition on Tuesday in a unanimous vote, following the resignation of former leader Andrew Little.
Little quit earlier in the day, according to local media, after taking responsibility for the Labour party's continued poor polling.
Just hours into her new role as alternative prime minister, Ardern was asked on current affairs show "The Project" about potentially juggling motherhood with her professional responsibilities.
"A lot of women in New Zealand feel they have to make a choice between having babies and having a career ... is that a choice that you feel you have to make or already made?" host Jesse Mulligan asked Ardern, after admitting some of his colleagues had said he shouldn't raise it.
Ardern said she had no problems with being asked the question. "My position is no different to the woman who works three jobs, or who might be in a position where they're juggling lots of responsibilities," she said.
"You've just got to take every day as it comes and see if you can make the best of the lot you're given."
But on Wednesday morning, speaking to New Zealand's "AM Show," Ardern took a stronger stance on the issue.
"I elected to talk about it, it was my choice ... but for other women it is totally unacceptable in 2017 to say a woman should have to answer that question in the workplace," she said forcefully.
"It is a woman's decision about when they choose to have children. It should not predetermine whether they should have a job or be given job opportunities."
Ardern has previously said she would like to have children,
but added it would be hard given the demands of her career.
A number of New Zealand commentators and social media users condemned questioning a female leader over her plans for children, saying such questions would never be asked of a male politician.
Online news site stuff.co.nz ran an opinion piece entitled, "No, we don't need to know about Jacinda Ardern's baby plans. Ever."
"I clearly recall the time (New Zealand prime minister) Bill English was asked how he was going to balance the national books and his hectic home life ... oh wait no I don't because it never happened," Kylie Klein Nixon wrote on their site.
Ardern is not the first female political leader to face questions over her motherhood plans.
In Australia, former prime minister Julia Gillard was regularly criticized for not having children. One conservative senator said she was "deliberately barren"
Ardern stepped into the role at a difficult time, just under two months from the next general election on September 23. The Labour party has been out of power since 2008.
Ardern is only the second female leader of the Labour party.