The Hollywood actress Angelina Jolie has undergone a double mastectomy to reduce her chances of getting breast cancer. The 37-year-old partner of Brad Pitt and mother of six children explained her reasons for having the surgery in the New York Times, saying her doctors estimated she had an 87% risk of breast cancer and a 50% risk of ovarian cancer. "I decided to be proactive and to minimise the risk as much I could," she wrote.

Jolie - one of the world's biggest movie stars - began the process in February and completed it in April. In a piece entitled My Medical Choice, the actress recalled how her mother fought cancer for nearly a decade before dying at the age of 56. "The truth is I carry a 'faulty' gene, BRCA1, which sharply increases my risk of developing breast cancer and ovarian cancer," she said.

Following the double mastectomy, Jolie says her chances of developing breast cancer have dropped from 87% to under 5% and she praised her partner Brad Pitt for his love and support throughout the procedure. "For any woman reading this, I hope it helps you to know you have options," Ms Jolie went on to say "I want to encourage every woman, especially if you have a family history of breast or ovarian cancer, to seek out the information and medical experts who can help you through this aspect of your life, and to make your own informed choices."

Emma Parlons, a 38-year-old mother from London who had the operation three years ago, welcomed Angelina's decision, telling BBC News, "If somebody said your flight across the Atlantic was 86% likely to come down, you wouldn't get on that plane would you?"

The Oscar-winning actress and director has long campaigned for humanitarian causes and is one of the UN's special envoys. She recently visited the Democratic Republic of Congo with UK Foreign Secretary William Hague and attended the G8 summit of foreign ministers in London to raise awareness over sexual violence in conflict. She also helped to launch a charity to fund girls' education in Pakistan.

She has three biological children and three adopted children with Brad Pitt. She recently completed work on Robert Stromberg's Sleeping Beauty tale Maleficent, told from the perspective of the princess' evil nemesis. Co-starring Juno Temple and Elle Fanning, the fantasy movie hits theaters in the U.S. on July 2, 2014.

Angelina JolieAngelina Jolie At The G8 Summit At Lancaster House In London

Angelina Jolie
Angelina Jolie At The 2013 American Society of Cinematographers Awards

Angelina Jolie
Angelina Jolie At The Third Annual Women In The World Event

Angelina Jolie
Brad Pitt [L] and Angelina Jolie [R] At The Academy Awards In 2012

Angelina Jolie
Angelina Jolie At The Screen Actors Guild Award In 2012