New Zealand’s Prime Minister Jacinda Ardern has been joined by her baby daughter Neve in a history-making visit to the United Nations in New York.

It is the first time a world leader has brought a newborn baby to the general assembly meeting.

Ms Ardern, there to give a speech at the Nelson Mandela peace summit, was also joined on the floor of the general assembly by Neve’s dad, Clarke Gayford.

Before she spoke, she played with three-month-old Neve, who then stayed on her father’s lap for the duration of the speech.

Official photographs of the event are believed to be the first to capture baby Neve’s face since she left hospital in Auckland with her parents after her June 21 birth.

Later on, Ms Ardern appeared on US NBC’s Today show – where she was asked if it was harder to govern New Zealand or take her daughter on a 17-hour flight. With a laugh, she said both felt “on-par”.

“There’s that look you get when you walk onto a plane with a little one, that stare you get from other passengers,” she said. “I did actually apologise in advance.”

“What is harder: running a country or taking a 3-month-old on the 17-hour flight to get here?” @savannahguthrie asks New Zealand Prime Minister @jacindaardern pic.twitter.com/LYkObhcSGP

— TODAY (@TODAYshow) September 24, 2018

Ms Ardern revealed that juggling parenthood and the prime ministership had “met my expectations” but the joy she felt at Neve “had far surpassed my expectations”.

But she also downplayed her own role, saying she was not the “gold standard” in parenting and she got lots of extra support that other parents did not have.

Mr Gayford is a fishing television presenter who has put his career on hold to be Neve’s primary carer. He has travelled with Ms Ardern to New York to look after the baby.

Just last week, Mr Gayford told Britain’s Grazia magazine that raising Neve was “so much more than a job”.

“I have no doubt I’ll look back on it as the best thing I’ve ever done,” he said. “But ask me again once I’ve had a full night’s sleep.”

Gayford posted a photo on Twitter on Monday of Neve’s security pass, which reads “first baby”.

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 21st. pic.twitter.com/838BI96VYX

— Clarke Gayford (@NZClarke) September 24, 2018

Earlier, Ms Ardern – described this year by Vogue magazine as “the anti-Trump” – caused more of a traditional political stir when she said New Zealand would not sign up to the US call for global action on the war on drugs.

US President Donald Trump’s “Global Call to Action on the World Drug Problem” document seeks a commitment towards a crackdown on supplying and smuggling drugs, with a focus on synthetic substances.

Ms Ardern said New Zealand had distinct challenges around the types of drugs that were causing issues – but also wanted to take a “health approach” with its domestic policy.

“We want to do what works, so we are using a strong evidence base to do that,” she said.

“It’s not our intention to [sign up] and there are a number of other countries who haven’t either.”

The US says 124 countries have already agreed to the document, which is being promoted by Mr Trump this week.

In the lead-up to the general assembly, the US ambassador to the United Nations, Nikki Haley, said Mr Trump would make it clear the US would “be generous to those that share our values”.

Ms Ardern, who is in New York for six days, will also make a case for global co-operation on issues such as climate change, human rights and poverty during her visit.

She said her direct interactions with Mr Trump during her visit – at a reception and leaders’ event – would likely be minimal.

New Zealand will spend $NZ300 million ($A275 million) on global climate change work in four years as it continues to press the need for a trans-Tasman focus on the Pacific.

-with AAP