Ardern said Prince Harry and Markle were happy their wedding was being acknowledged in New Zealand through a donation to Pillars.
"The couple are both very interested in initiatives that support vulnerable children and young people."
The couple will wed at St George's Chapel, Windsor Castle, on Saturday. It will be broadcast live, with Kiwis able to tune in on Saturday evening (NZT).
On...Winston Peters as acting Prime Minister
Ardern said she has outlined in a letter Deputy Prime Minister Winston Peters' duties as acting Prime Minister while she is on parental leave.
They will include day to day duties such as attending official engagements and answering questions in the House.
Ardern will continue to be consulted while she is on leave.
Ardern said the duties of acting Prime Minister were set out in the Cabinet Manual. Ardern said while childbirth was not unprecedented, she acknowledged that a Prime Minister having a baby while in office was.
It was unnecessary for Peters to move to her ninth floor office while she was on leave.
Peters would not be sworn in.
Ardern would remain Prime Minister for the period she was on leave.
Ardern objected to the letter being described as a 'behave yourself' contract.
She expected to be back at work within the six-week period. "We're hoping for the best, preparing for the worst".
"Simply our roles will reverse for a while".
Peters said the letter was crafted by both him and the Prime Minister.
If an issue arose in which Peters needed to go overseas, Kelvin Davis would take over.
Peters said he was ready for the role, having done it 22 years ago.
He was asked about his upcoming trip to China.
He said trade and North Korea would be topics to be covered on his trip, next week.
Ardern said New Zealand was not naive to political interference, and it was not "down to one lone state actor".
Peters said he would be meeting his Chinese counterpart and other organisations, officials and ministers.
Asked whether he would be drumming up interest in investment in New Zealand infrastructure projects, Peters said that was not his role but would ensure the message from ministers was carried.
On...the spread of mycoplasma bovis to Waikato
Ardern said MPI was working hard on containment plans.
"This Government having to pick up the pieces of neglect and underinvestment, it's shameful."
The disease posed no threat to humans but it needed to be brought under control.
Ardern said it was brazen for the issue to be made political given it arose some time ago.
"We're not giving up on all the options on eradication".
The Minister for Agriculture was spending "almost 100 per cent" of his time on the issue.
"There was a system in place. It failed abysmally."
At top of mind was the welfare of farmers, Ardern said.
Asked about the official Information Act, Ardern said the Government was looking at standardising the use of the OIA.
On...the 2018 Budget
The Prime Minister said Budget 2018 would build strong foundations for the future in core services such as health and education but reiterated it would not happen in one Budget.
She said she was concerned about the recent bombings in Indonesia and the use of children was "appalling".
The Prime Minister finished her press conference by talking about measures targeting low income households, such as the winter energy payment, which comes into effect on July 1.
