Jacinda Ardern pregnancy: What should she call her baby?

Jacinda Ardern has announced her pregnancy on Friday in a shock announcement.

"Clarke and I are really excited that in June our team will expand from two to three, and that we'll be joining the many parents out there who wear two hats," she said on Facebook.

"I'll be Prime Minister AND a mum, and Clarke will be "first man of fishing" and stay at home dad."

But while Ms Ardern and her partner Clarke Gayford celebrate, they also face a tough choice - what to name the new baby.

If it's a boy, Oliver could be the top choice. 2017 was the fifth year in a row it topped the list of New Zealand's most popular baby names, with 314 of them joining the country.

And if it's a girl, Charlotte would have a strong chance, with 277 added to our population.

Top baby names in 2017

Girls: Charlotte, Harper, Isla, Olivia, Ava, Amelia, Mia, Mila, Sophie, Emily.

Boys: Oliver, Jack, Noah, William, Hunter, James, George, Mason, Lucas, Arlo.

Or the PM could reflect our ethnic diversity and choose a Māori name. Māori Language Commission chief Ngahiwi Apanui says more and more children are receiving Māori names as awareness and value for te reo Māori grows.

Top five Māori baby names in 2016

Girls: In NZ -  Maia, Ariana, Manaia, Anahera, Hana; Overseas - Maia, Ariana, Hei, Manaia, Aroha.

Boys: In NZ - Nikau, Ari, Karui, Manaia, Te Ariki; Overseas - Kai, Manaia, Ari, Nikau, Tamati.

However she might want to avoid any on the list of Australia's top 20 bogan baby names - which include options like Kaos, Slash and Xytl - or the Department of Internal Affairs' list of annual list of names that were declined.