Ardern's pregnancy has been followed around the world, with many hoping the 37-year-old will become a role model for combining motherhood with political leadership.
Her partner, Clarke Gayford, hosts a fishing documentary series, but will give that up to be a stay-at-home dad.
New Zealand's Prime Minister Jacinda Ardern was regaining her strength with macaroni and cheese on Friday and planned to spend at least one more night in an Auckland public hospital with her newborn girl.
Make no mistakes, Templer doesn't regret her decision to go back to work so soon after having her son, nor does she look down on Ardern for her's.
Ms Ardern gave birth to a healthy baby girl on Thursday, the first for her and partner Clarke Gayford.
Remarkably, Ardern's baby's June 21 birthday is the same as Benazir Bhutto.
"We believe the merino blanket the Prime Minister has in her hand in the Instagram photo is the one we gifted her".
Their daughter was born at 4.45pm at Auckland City Hospital and weighs 3.31kg.
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Ross Ardern said the baby girl would be good company for their other two grandchildren.
"I'll probably try sneak in my name somehow", she said at the time. In the United States, several politicians have made headlines for their pregnancies in recent years, including Sarah Palin, who as governor of Alaska delivered a baby in 2008, and Sen.
"Congratulations to Prime Minister @jacindaardern on the wonderful news", she wrote.
"For New Zealand, these events and the way our country has greeted them will be seen as inspirational by all who advocate for gender equality and women's empowerment", Ms Clark said. Ardern plans to take six weeks of leave before returning to work.
Jennifer Curtin, a professor of politics at the University of Auckland, said there was symbolic importance in Ms Ardern giving birth as it showed political parties around the world that it was fine to have younger women as candidates.
Before Ardern, former Pakistan Prime Minister Late Benazir Bhutto was the only woman to have undergone labor while in power.
Templer said it was nearly harder now than when her children were babies to be away from them.
Acting Prime Minister Winston Peters led the well wishes from the Government, saying it's a "happy day", along with members of the opposition and those within the Prime Minister's own party, including Finance Minister Grant Robertson.