NZ PM Jacinda Ardern's baby daughter watches her first United Nations address

New Zealand's Prime Minister Jacinda Ardern has delivered her first speech at the United Nations – and her baby daughter got to be there to cheer her on.

It was a historic move, marking the first time a female leader has brought her child along to the United Nations General Assembly in New York.

Three-month-old Neve was held by her father, TV host Clarke Gayford, while Arden delivered a speech for the Nelson Mandela peace summit.

Seeing as the little one is still breastfeeding, the Prime Minister needed to bring her - as well as her partner and Neve's primary carer, Gayford - along to New York for the talk.

Ardern gave birth to Neve in June this year, and returned to work after six weeks of maternity leave.

Neve was even given her very own security pass, which very sweetly dubs her 'First Baby'.

Gayford tweeted a picture of the security pass with the caption, "Because everyone on twitter's been asking to see Neve's UN id, staff here whipped one up.

“I wish I could have captured the startled look on a Japanese delegation inside UN yesterday who walked into a meeting room in the middle of a nappy change."

"Great yarn for her 21^st," the proud dad added. We bet!

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As part of the trip, Ardern also appeared on the American TODAY Show to chat about juggling her high-profile appointment with her new job as a mum.

When asked what was more difficult, leading a country or taking a baby on a 17-hour flight, Ardern joked they were "on par".

Knowing what a hassle a newborn on a plane can be, she even apologised to her fellow passengers in advance.

Ardern is only the second world leader to have given birth while in office.