Jacinda Ardern has given her most detailed account yet of the week she was thrust into the top job of Labour leader.

It was Ms Ardern's birthday that former leader Andrew Little told her he was worried about the polls, and thought she should take over as leader.

She said from that day - the 26th July - until the first of August, she was asked every day, and said "no, no, no."

"There was lots of reasons for that, but the moment then when Andrew made that decision, then there was a role that I needed to step into - and there was no doubt in my mind that that was what I needed to do."

She revealed this at a school for solo mums today.

Ms Ardern told the young women in the room not to doubt themselves, or be afraid to take opportunities when they come to them.