Prime Minister Jacinda Ardern's pregnancy a hit overseas and in NZ

Political commentators are calling the Prime Minister's pregnancy announcement a genius move that even the most experienced spin doctor couldn't have conjured up.

News that Jacinda Ardern and her partner, Clarke Gayford, will be welcoming their first child in June was largely greeted positively both here and abroad.

International news channels went ga-ga over the Prime Minister's pregnancy story overnight.

World leaders also tweeted their congratulations, Canada's Justin Trudeau saying he hopes to meet the little angler one day.

"It's quite a story that I think will capture a lot of people's hearts throughout the world," says political commentator Dr Bryce Edwards. "She will become more of a global celebrity as a result."

Ms Ardern's pregnancy further enhances her star appeal. In March she'll grace the pages of US Vogue magazine.

Her baby's June arrival will mean more photo opportunities, closely following the birth of the third royal child for the Duke and Duchess of Cambridge.

Political commentators say being the first New Zealand PM to give birth while in office is a real boost for gender politics worldwide.

"It's going to become a symbol for women being able to do anything," says Dr Edwards.

"For women to be able to be in very high office or powerful jobs and be a mother and give birth, it's going to be symbolic for a lot of those gender issues we're looking at like pay equity."

This was no time for cheap political shots; congratulations rolled in across the political divide.

"Jacinda Ardern is capable of being our Prime Minister and a mother, and it will add insight and joy to her work and we should celebrate that," says Jenny Shipley, former National Party member and New Zealand's first female Prime Minister. 

National leader Bill English and his wife congratulated Ms Ardern and Mr Gayford on Facebook, but some comments on that post criticised the Prime Minister.

One said: "Call me old fashioned but I thought marriage came before children."

Another: "If they wanted to get pregnant maybe she should not have become leader of the Opposition knowing she may win the election and that she may become pregnant."

"For those who are seeing this as negative I really ask them to think about their sisters, and their daughters and their granddaughters," says Ms Shipley.

"How we would not want an outstanding young leader, even if we agree or disagree with her, to be able to separate motherhood and excellent performance?"

Dr Edwards says her six-week maternity leave once the baby is born is no major cause for concern.

"I don't think there's anything to worry about especially in constitutional terms. The show will continue to go on."

He predicts the next round of polling will see Ms Ardern go up in the preferred Prime Minister stakes.

"I don't think this is the result of any market research, but it's almost as if her best political marketers had come up with this dream scenario of 'have a baby while in office' because this will be magic for her."

The pregnancy news is now the gift that will keep on giving for the 37-year-old Labour leader.

"Over the next six months there's going to be all the focus on Jacinda Ardern's pregnancy, and then the birth and then the newborn baby, and then the toddler and so on," says Dr Edwards.

It means plenty of photo opportunities for Ms Ardern on the 2020 election campaign trail. But this time the baby she'll be kissing will be her own.

Newshub.