Former prime minister Helen Clark says the birth of Jacinda Ardern and Clarke Gayford's baby is sending a "very powerful" statement to the world on gender equality.
Prime Minister Ardern and her partner Gayford welcomed their first child, a baby girl, on Thursday.
She was born at Auckland City Hospital at 4.45pm, weighing 3.31kg (7lbs 5oz).
Clark, a former mentor and boss of Ardern, told Newstalk ZB there had been much interest across the globe in the birth, and it was sending a strong message about gender equality and choice.
"People are really interested in this first family and the statements they are making about gender equality and choice.
"It has generated huge news internationally, because it is so uncommon for a serving prime minister to give birth."
"Young women are very excited about it because, in a sense, it validates their desire to have both a career and a family."
Gayford, who has said he would a stay-at-home dad, was also sending a strong message it was acceptable for male partners to be fulltime carers.
"For gender equality and women choosing their own destiny, the symbolism is very powerful," Clark said.
"It is a message of global significance, that it is possible to be a mum and have a career, including in the fast lane.
"And that is the kind of message many young women want to hear, because they have been wondering, 'Can I do it?' They look at Jacinda and say, 'Yes I can'."
Former Pakistan prime minister Benazir Bhutto was the first modern head of government to give birth while in office, 27 years ago.
She gave birth to her daughter Bakhtawar on January 25, 1990, who in turn congratulated Ardern via Twitter yesterday.
Clark, who early in her political career had been told not being married to her now-husband Peter Davis would be an issue, said Ardern's pregnancy had also shown a "maturity" in New Zealanders.
"Kiwis have taken the pregnancy in their stride from day one. There has been a lot of excitement in the country, and that has spread around the world."
As leader of the country and a new mum, Clark believed Ardern would continue to take it all "in her stride".
"I think Jacinda has done an outstanding job.
"She took Labour out of the political death zone, to really a pretty good result.
"Then was able to successfully negotiate to be Prime Minister.
"She will take the new baby in her stride. She has a very supportive partner, who will be a stay-at-home dad, she'll get on with job and do as much at home.
"She will combine work and family like women the world over."
On a more personal level, Clark said she was "very excited by the news".
"I think it is wonderful for Jacinda and Clark. This is a much wanted-baby.
"My message is enjoy this moment, a time of great celebration in the family."