Princess Märtha Louise of Norway celebrates her 43rd birthday on 22 September.
To honour the Norwegian royal's birthday, HELLO! Online has gathered ten facts about the princess you may not have known.
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Princess Märtha Louise of Norway is fourth-in-line to the throne
1. Märtha Louise was born on 22 September 1971 in Oslo, as the first child of the then Prince Harald, who would eventually become King of Norway and his wife, Crown Princess Sonja. She has one younger brother, Crown Prince Haakon.
2. At the time of her birth only males could inherit the Norwegian throne, although in 1990 the constitution was changed meaning Märtha Louise was in line for the throne, however, Crown Prince Haakon still took precedence.
3. As with many royals in Europe, the princess is also in line for the British throne, as a great-great-granddaughter of King Edward VII.
Princess Märtha Louise of Norway and her author husband Ari Behn
4. In May 2002, the princess married author Ari Behn in a ceremony in Trondheim, Norway, surrounded by royals from around the world, including the Earl and Countess of Wessex, Crown Princess Victoria of Sweden and the then Prince Felipe of Spain.
5. Märtha Louise and Ari welcomed their first daughter, Maud Angelica, in April 2003, who was followed by Leah Isadora and Emma Tallulah, in April 2005 and September 2008, respectively.
6. In 2002, after discussion with her father King Harald, Märtha Louise's style of 'Her Royal Highness' was replaced with 'Her Highness' which allowed her more freedom to work on her own business away from her constitutional role as a princess.
7. Despite scaling back her royal duties, the princess still represents her father at some engagements and Märtha Louise takes a keen interest in improving the quality of life for people with disabilities.
Princess Märtha Louise of Norway and Ari Behn with their three children
8. The princess shares her birthday with Harry Potter star Tom Felton, singer-turned-actress Billie Piper and Italian tenor Andrea Bocelli.
9. Despite being a certified physiotherapist, Märtha Louise decided to set up her own entertainment business. The princess was inspired by her fascination of Norwegian fairy tales and her love of folk music.
10. In 2007, the princess was editor of the book Prinsesse Märtha Louises eventyrlige verden, Eventyr fra jordens hjerte, Rodinia which featured 67 fairy tales from 50 countries around the world.