Queen Elizabeth has congratulated Prime Minister Jacinda Ardern on the birth of her baby girl.
The Prime Minister's Office confirmed to 1 NEWS that Ms Ardern received a private congratulatory message from the Queen.
The Queen's message was communicated via a letter through Britain's Cabinet Secretary.
In April Ms Ardern had a private audience with the Queen in London while she was attending the Commonwealth Heads of Government Meeting.
Last night, news of the first baby of New Zealand was revealed on Jacinda Ardern's Instagram.
"Welcome to our village wee one," Ms Ardern wrote.
"Feeling very lucky to have a healthy baby girl that arrived at 4.45pm weighing 3.31kg (7.3lb) Thank you so much for your best wishes and your kindness. We're all doing really well thanks to the wonderful team at Auckland City Hospital."
Ardern now becomes the first elected world leader to take maternity leave - and only the second to have a child while in office - having handed over her duties to her deputy earlier in the day.
New Zealanders will have to wait until at least tommorow for a public appearance of Ms Ardern and her new baby with the PM deciding to rest up in hospital today.