Prime Minister Jacinda Ardern has a "contingency plan" in case her baby doesn't arrive on its due date - keep working.

Speaking to Stuff in her weekly interview slot the prime minister said she would be working as late as humanly possible.

"I'm due on the 17th of June, and that week I'll be working right through. In fact I've already made a few contingency plans to be able to keep going until I'm actually physically in labour, because why waste time?" Ardern said.

CAMERON BURNELL/STUFF. Prime Minister Jacinda Ardern chats live with Tracy Watkins.

Her child is due on June 17, exactly one month after the full budget.

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Ardern said Kate the Duchess of Cambridge's early exit from the hospital after having her third child "set a ridiculously high bar that I will not be following myself."

STUFF Prime Minister Jacinda Ardern has a "contingency plan" in case her baby doesn't arrive on its due date - keep working.

"No one should expect me to be stepping out onto a balcony and waving."

Ardern is planning to take six weeks of leave after having her child, with deputy Prime Minister Winston Peters acting in her stead.

She will still be contactable during that time however, so Peters will be able to reach her if major decisions come up.

Ardern said it felt like "ages" until she actually went on leave.

"It's a really really long time and I don't want to think about it."

Ardern has been cleared to fly domestically right up to her due date.