World leaders are congratulating Prime Minister Jacinda Ardern and Clarke Gayford for the birth of their baby girl on Thursday at 4.45pm (NZT).
The healthy baby girl weighed 3.31kg (7.3lb).
This makes Ms Ardern the second world leader ever to have a baby while in office, with Pakistan Prime Minister Benazir Bhutto giving birth in 1990.
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The Prime Minister has recieved an emailed letter from the Queen, congratulating her on the new arrival.
Congratulations and best wishes are also flooding Twitter.
Former Prime Minister Helen Clark has congratulated the new mother, "Congratulations to Jacinda Ardern and Clarke Gayford on the birth of their daughter today."
"What a proud day for Jacinda and Clarke and for us all. New life, new hope. Parenting arrangements are #gender equality in action. This is 21st C NZ. #Proud Kiwi"
UK Prime Minister Theresa May also sent her best wishes "Congratulations to Jacinda Ardern and Clarke on the birth of your little girl."
Canadian President Justin Trudeau, also Tweeted Ms Arden with a tip for parenthood.
"Welcome to the wonderful world of parenting Jacinda Ardern & Clarke! Pro tip, Jacinda: Briefing notes make excellent bed time stories."
The Prime Minister of Ireland Leo Varadkar also congratulated the couple.
“Congrats Jacinda Ardern to you and Clarke on the birth of your baby girl. No doubt you’ll be a great mum. Sending best wishes from Ireland.”
Iceland Prime Minister Katrin Jakobsdottir is also happy for the new parents.
Bskhtawar B-Zardari who is the Daughter of former Pakistan Prime Minister Benazir Bhutto who was the first Prime Minister to give birth while in Parliament in 1990, has also congratulated Ms Ardern.
"Congratulations Jacinda Ardern on the birth of your daughter! Reposting this, relevant as ever, "Benazir Bhutto showed you can be a mother and Prime Minister"
Opposition Party leader Simon Bridges has also shared his best wishes "Congratulations on the birth of your baby girl. Natalie and I wish you every happiness."
Greens MP Marama Davidson also shared her congratulations "Nau mai ki Te Ao Marama te pepi hou o Te whare Paremata. Welcome to the world little one, and congratulations Jacinda and Clarke!"
US ambassador for New Zealand and Samoa, Scott Brown sends Ms Ardern his best wishes.
"Wonderful news! Huge congrats to Prime Minister Jacinda Ardern and Clarke Gayford on the birth of their baby girl! A warm welcome to the world! Wishing the family health, happiness, and all joy in the world. "
Leader of the UK Labour Party Jeremy Corbyn also tweeted the Prime Minister.
"Congratulations to New Zealand's Labour Prime Minister Jacinda Ardern on giving birth to a baby girl. It was a real pleasure to meet Jacinda with Emily Thornberry in April in London. The whole of UK Labour sends you our best wishes."