Finland is set to have the world's youngest prime minister after 34-year-old Sanna Marin was chosen as the new leader of the Social Democratic party.

The Helsinki-born former transport minister will be the country's third female government leader, after she narrowly beat rival Antti Lindtman to take over the government's top post from incumbent Antti Rinne.

Ms Marin, an MP since 2015, has previously been the party's vice chairwoman and will become the world's youngest sitting prime minister.

The mother-of-one - who shares 22-month-old daughter Emma Amalia Marin with husband Markus Räikköne - will lead a centre-left coalition with four other parties which are all headed by women, three of which are under 35.

According to Finish media, Ms Marin was brought up in a 'rainbow family' by her mother and her female partner. 

She lived in Espoo and Pirkkala before moving to Tampere, where she became the first person in her family to go to university. 

Ms Marin is certainly a politician who will appeal to the millennial 'Instagram generation'. During her rise to success in the political field she has charted her pregnancy journey on her Instagram page, sharing selfies of her pregnancy bump and even a candid breastfeeding shot.

She's also shared poolside shots from a romantic holiday to Italy in July 2017, during which she and Markus travelled to Portofino, Rome, Sardinia and Veneto, and snaps from Pride events, where she showed her support for same-sex unions.

And Ms Marin appears to have a sweet tooth, having shared fun photos of her tucking into ice cream and candy floss.

In 2015 Ms Marin told the Menaiset website that as a child she felt 'invisible' because she was unable to talk openly about her unconventional family.

'The silence was the hardest,' she said. 'Invisibility caused a feeling of incompetence. We were not recognised as a true family or equal with others. But I wasn't much bullied. Even when I was little, I was very candid and stubborn. I wouldn't have taken anything easy.' 

She also admitted that she never expected to get into politics, telling the publication: 'When I was in high school, I felt that the people who make politics are quite different and come from different backgrounds than I am. At that time, I didn't think it was possible to get involved myself.'

Ms Marin, who spent her teenage years working in a bakery, added that her mother has always been very supportive and made her believe she could do anything she wanted. 

Speaking after her appointment, Ms Marin said she has 'never thought' about her age or gender, adding: 'I think of the reasons I got into politics and those things for which we have won the trust of the electorate.'

She told reporters: 'We have a lot of work to do to rebuild trust.'

The mother-of-one was elected to the City Council of Tampere in 2012 and became its chairperson in 2013 - a role she held until 2017, when she was re-elected.

In 2014 she was elected second deputy chairperson of the Social Democratic Party and in 2015 she was voted into the Parliament of Finland from the electoral district of Pirkanmaa. 

She became the Minister of Transport and Communications in June earlier this year.

Finland, which has a population of 5.5 million, currently holds the European Union's rotating presidency until the end of the year. MPs are likely to approve the appointment of Ms Marin and her new government quickly so she can represent Finland at next week's EU leaders' summit in Brussels.

The current youngest world leader is Ukraine's Oleksiy Honcharuk, 35, followed by North Korean dictator Kim Jong-un, 35, El Salvador's President Nayib Bukele, 38, and New Zealand's Jacinda Ardern, 39.