Ms Ardern gave birth in Auckland Hospital, the country's largest public hospital, with her partner, television presenter Clarke Gayford, at her side.
In a post on her official Instagram account, Ardern said the baby arrived at 4.45 pm local time, weight 3.31 kilograms (7.3 pounds).
But while Ms Ardern has been working to assure the nation, Mr Peters has been causing a stir.
Ardern thanked everyone for their kindness and said they were all doing really well.
Benazir Bhutto gave birth while serving as Pakistan's prime minister in 1990, in a dramatically different political climate in which her opponents used her pregnancy as a reason to demand her dismissal.
Ardern turned around support for Labour after being elected leader less than eight weeks before the Sept 23 election, stirring up what media dubbed "Jacinda-mania" with her appeal to younger voters and her promises to tackle social issues.
At the same time, Ardern does not plan to entirely shirk her duties while on leave.
"The prime minister having a baby while in office is a symbolically significant moment for our country, women in particular, and sends an important message that caring for children is one of the most important jobs in the world", said Davidson.
Mr Peters said: "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.
The intervening months have seen a frenzy of excitement from New Zealanders, many of whom took to the web on Thursday to express their happiness.
Ardern's office confirmed just after 6 a.m. she'd arrived at the hospital with partner Clarke Gayford.
Prior to her, Queen Elizabeth II gave birth to Prince Andrew in 1960 and Prince Edward in 1964 after her ascension to the throne in 1952.
She plans to take six weeks off work.
"Congratulations to Prime Minister @jacindaardern on the wonderful news", she wrote.
"I do not want to create a false impression that all women should be super-human or super-women", she said recently.
Pro-Brexit tabloid the Sun warned lawmakers on Tuesday's front page that they had a choice: "Great Britain or great betrayal". Ukip leader Gerard Batten said: "The only "meaningful vote" was the verdict of the people in referendum of June 23 2016".
A penalty scored by Antoine Griezmann and Australia own goal were the difference, but the performance was lackluster. But no player is more important to Peru than striker Paolo Guerrero , who came off the bench against Denmark.
Maguire, Stones and Kane, in particular, offer an aerial threat at set-pieces which England believe they can fully exploit. Speaking to BBC One after the Tunisia win, Kane said: "We have shown resilience for a while now since the gaffer come in".
On Tuesday, the Department of Homeland Security said 2,342 children have been separated from their parents since last month. A subsequent ruling in 2016 bars the government from keeping children in family detention centers for more than 20 days.
The equivalent value of €2.8 billion worth of United States goods that will be hit by import duties charged by the EU. The new duties have been imposed as tensions over trade continued to grow between the United States and China.
Baijal said that it was a matter of pride and privilege that yoga was being practised in 200 countries by crores of people. Yoga might be India's greatest cultural export, but brand India itself is encouraging more yogapreneurs every year.
But it wasn't long before the first lady's controversial jacket threatened to overshadow the entire goodwill junket to the border. Melania and her husband are reported to be visiting the United Kingdom on 13 July, and are even expected to meet the Queen.
Another added: "God forgive me, the priest was getting kicked up and down the chapel like a football if that was my child". A video of a Catholic priest slapping a crying baby in the face during a baptism has surfaced online.
The cover is for the July 2 edition of the magazine, which will appear on newsstands the week of Independence Day. I asked her, why? First lady Melania Trump visited an immigration detention facility on Thursday.
Trump Signs Order to 'keep Families Together'
She also ruled that the announced decree would replace one crisis with another: "Children have no place in prison", she said. Marshals Service and sends many children to facilities run by the Department of Health and Human Services.
Trump threatens tariff on all European cars
Trump ran for the presidency on a vow to topple seven decades of American policy that had favored ever-freer trade among nations. And he is threatening to impose another national security-based tariff on imports of cars, trucks and auto parts.
Oil complex rallies despite China/US trade tension - Oil
Non-OPEC members including Russia , Oman and Mexico also agreed to cut 558,000 bpd off their production to stabilise the market. Retail prices of petrol and diesel are ruling at Rs 75 a litre and Rs 68 a litre amid the global surge in crude prices.
Governor rule imposed in India-occupied Kashmir
He said the BJP faced some difficulty in implementing developmental projects as some ministries were not with the party. The BJP said it had become "untenable" for the party to continue in the alliance government.
Phanatic's flying hot dog hurts Phillies fan
She was cleared, but sustained a small hematoma in her eye, an injury which needs to be iced every 20 minutes. A shoulder injury kept her from catching the hot dog or swatting it away.
Instagram launches IGTV, a standalone app for long-form videos
Karen Leung expects to try it for an account she runs devoted to her 5-year-old Shiba Inu named Nacho , which has 7,000 followers. Instagram chief executive Kevin Systrom announced the milestone as he unveiled the new video application known as IGTV.
Google rolls out Android Messages for web
The Messages for the web is already being rolled out, and you can update to the latest version of the Android Messaging app here. The company has added that the QR scanner might not be live across the board as the rollout comes in stages.