The new royal baby is already being showered with presents, including from New Zealand.
Their Royal Highnesses, the Duke and Duchess of Cambridge, welcomed a baby boy overnight.
A collection of New Zealand childrens' books and a blanket made of New Zealand wool will be sent to the baby, Ms Ardern told The AM Show.
The Prime Minister also added a personal gift.
"I've had a family member of mine whip together a personal gift... a white linen romper with a Buzzy Bee lining on it."
Ms Ardern revealed the mastermind behind the romper is her sister-in-law,
"She's an excellent sewer."
She said a note will be added to indicate the personal nature of the gift.
The selection of children's books were chosen by author Kate De Goldi:
- My New Zealand ABC Book; learn the alphabet with art and objects from Te Papa; text by James Brown
- My New Zealand 123 Book; learn counting with the art and objects from Te Papa; text by James Brown
- My New Zealand Colours Book; learning colours with the art and objects from Te Papa; text by James Brown
- Nga Ahua-Shapes by Kitty Brown & Kirsten Parkinson
- The Word Witch by Margaret Mahy; illustrated by David Elliott
- The Fish of Maui by Peter Gossage
- Slinky Malinki by Lynley Dodd
- Bad Dog, Flash! by Ruth Paul
- The Longest Breakfast by Jenny Bornholdt; illustrated by Sarah Wilkins
- The House that Jack Built by Gavin Bishop
- The Duck in the Gun by Joy Cowley; illustrated by Robyn Belton
- Kiss, Kiss, Yuck, Yuck by Kyle Mewburn; illustrated by Ali Teo & John O’Reilly
- The Kuia and the Spider by Patricia Grace; illustrated by Robyn Kahukiwa
- Talia by Catherine Hannken; illustrated by Trish Bowles
- So Many Wonderfuls by Tina Matthews
As to if she herself will receive a present from the royals, the Prime Minister laughed and said she wasn't expecting anything.
The name of the royal baby is yet to be revealed.