New Zealand prime minister Jacinda Ardern has given birth to a baby girl.

Ms Ardern posted a photo on her Instagram account showing her and partner Clarke Gayford with the baby at Auckland City Hospital.

She wrote that she was feeling very lucky to have a given birth to a healthy girl, and that their daughter arrived at 4.45pm weighing 7.3lb.

She thanked everyone for their kindness and said they were all doing well, and also thanked the team at the hospital.

The 37-year-old would become just the second elected world leader in modern times to give birth while in office, after the late Pakistan prime minister Benazir Bhutto gave birth to daughter Bakhtawar in 1990.

New Zealand’s deputy prime minister, Winston Peters, will take over to allow Ms Ardern to take six weeks of maternity leave, but she had said in a statement that she intended to be “fully contactable” during her maternity leave.

At the end of her leave she intended to resume “all prime ministerial duties”, she added.