Davidson and other politicians who had children in office

Ruth Davidson and partner Jen Wilson have announced they are to have a child

Ruth Davidson's announcement has highlighted how rare it is for a sitting politician to give birth, but she is not the first to have a child while in her post.

She said she would be taking some maternity leave like "thousands of working women do every year".

Prime Minister of New Zealand Jacinda Arden announced her pregnancy in January this year.

Ms Ardern said she and her partner, Clarke Gayford, are expecting their child in June, after which she planned to take a six-week break.

New Zealand's prime minister Jacinda Ardern is thought to be the second leader to announce a pregnancy while in office

The 37-year-old is thought to be the second leader to announce a pregnancy while in office.

The first was former Pakistan Prime Minister Benazir Bhutto, who gave birth in office in 1990.

Her second child Bakhtawar is believed to the first born to a world leader who had been democratically elected.

Senator Tammy Duckworth recently made history becoming the first US senator to give birth while serving.

After rules banning children were changed, she entered the Senate floor with her infant daughter so she could cast a vote.

Benazir Bhutto was thought to be the first female world leader to have a child in office

In the UK, no major party leader has been in their post while pregnant, although Margaret Thatcher became a grandmother while prime minister.

Yvette Cooper was the first UK cabinet minister to take maternity leave while in post as public health minister in 2001. Her husband, Ed Balls, also took paternity leave.

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Ms Cooper later revealed she felt "cut off" by Whitehall officials when she took maternity leave for a second time in 2004.

Labour's Yvette Cooper was the first cabinet minister to take maternity leave in 2001

Jo Swinson also gave birth while women and equalities minister, and in 2016, Sports minister and Tory MP Tracey Crouch gave birth to her son, Freddie, while in office.

SNP minister Aileen Campbell became the first member of the Scottish government to take maternity leave in 2014.

The MSP told the BBC: "This is politics reflecting real life, this is something that many women and many families have to do and I'm looking forward to having a bit of time with my family and the new arrival."

Former Labour government minister Ruth Kelly had her first child just 11 days after she was first elected to Westminster.

She went on to have three more children within five years.

In 2015, Labour frontbencher Rachel Reeves rejected suggestions that she would not be able to give a top government job her "full attention", while pregnant.