WELLINGTON - New Zealand Prime Minister Jacinda Ardern gave birth to her first child in Auckland on Thursday afternoon.

A 3.31-kg baby girl was born at 4:45 pm local time at Auckland City Hospital, making Jacinda Ardern the first NZ PM to give birth while in office and among few worldwide.

Social media went frenzy Thursday morning after media outlets broke the news that 37-year-old Ardern has been in labor at Auckland City Hospital.

"Thank you so much for your best wishes and your kindness. We're all doing really well thanks to the wonderful team at Auckland City Hospital," Ardern said on social media after giving birth to the baby.

Ardern announced her pregnancy a few months after leading Labor Party to successfully negotiate a coalition government deal with key minority party led by veteran politician and incumbent Vice Prime Minister Winston Peters.

Ardern's partner Clarke Gayford, 40, was a fishing series TV host and would nanny the new-born according to their previous plan.

After giving birth, Ardern will take a six-week maternal leave, during which her deputy Peters steps in as Acting Prime Minister.