Deputy Prime Minister Winston Peters has been made Acting Prime Minister and will run the country for the next six weeks while Ardern takes maternity leave, the statement says.
Not surprisingly, the PM's office won't be giving any more formal announcements until Ardern and her partner Clarke Gayford get to officially announce the birth of their child, the sex of which they haven't let slip yet.
New Zealand Prime Minister Jacinda Ardern speaks during a press conference with German Chancellor Angela Merkel after a meeting at the chancellery in Berlin, Germany, April 17, 2018.
The much-anticipated arrival has gone global, as worldwide media outlets keep track of what is unfolding at Auckland Hospital.
The Prime Minister said today her and partner Clarke Gayford are excited "to do this".
Prime Minister Jacinda Ardern announced her pregnancy with a post on social media.
"It's a happy day and on behalf of the coalition government we wish her and Clarke all the very best", Peters said in an emailed statement. Although she will still be consulted for some relatively major decisions, like national security issues...no big.