Actress and humanitarian Angelina Jolie has revealed she had a preventive double mastectomy after learning she carried a gene that dramatically increased her risk of developing breast cancer.

Jolie made the revelation in an op-ed published in . In the piece, entitled “My Medical Choice,” the Oscar-winner says she had three operations between early February and late April to remove and reconstruct both breasts.

Jolie, 37, said she carries the BRCA 1 gene mutation that gives her an 87 per cent chance of developing breast cancer.

Jolie said it was losing her mother at a young age to cancer and fearing leaving her own six children without their mother that informed her decision.

"My mother fought cancer for almost a decade and died at 56," Jolie wrote. "She held out long enough to meet the first of her grandchildren and to hold them in her arms. But my other children will never have the chance to know her and experience how loving and gracious she was."

"They have asked if the same could happen to me,” Jolie added.

Jolie’s mother, French actress Marcheline Bertrand, died in 2007. She raised Jolie and her brother after divorcing their father, American actor Jon Voight.

In the piece, Jolie goes into considerable detail about her experience.

"My own process began on Feb. 2 with a procedure known as a 'nipple delay,"' she wrote, "which rules out disease in the breast ducts behind the nipple and draws extra blood flow to the area."

Two weeks later, she wrote, she had all of her breast tissue removed in a major operation that seemed “like a scene out of a science-fiction film.”

Nine weeks after that she had surgery to reconstruct her breasts with implants.

Jolie said that although she remained private about her ordeal as she went through it, she wanted to share her story to help other women facing the same decisions.

"I wanted to write this to tell other women that the decision to have a mastectomy was not easy. But it is one I am very happy that I made," Jolie wrote. "My chances of developing breast cancer have dropped from 87 per cent to under 5 per cent. I can tell my children that they don't need to fear they will lose me to breast cancer."

Jolie said she had the full support of her partner Brad Pitt. The actor was with her during “every minute of the surgeries,” which she had at the Pink Lotus Breast Center in Southern California.

Breast cancer experts say surgery isn’t the only option for women who are at risk of developing the disease. They can opt for more frequent screening with mammograms and ultrasounds.

However, Dr. Steven Narod of Toronto’s Women’s College Hospital points out that surgery often gives women greater piece of mind.

“When a woman undergoes preventive surgery, she undergoes a tremendous sense of relief and satisfaction in knowing the risk has been taken care of and that she has done everything possible to reduce that risk,” Narod told Âé¶čŽ«Ăœ.

Jolie is best known as an actress who won an Oscar for 1999’s “Girl, Interrupted,” but has also done extensive humanitarian work in recent years on behalf of the United Nations. Her work with the UN has taken her to war-torn regions as an ambassador for refugees.

In March, she travelled to Africa on behalf of the UN, and never let on that she was in between surgeries.

“She gave no sign that she was undergoing such treatment and I think she’s a very brave lady,” said British Foreign Secretary William Hague, who was travelling with Jolie at the time.

Ottawa resident Lianne Degen chose to have a preventive double mastectomy and reconstructive surgery in 2009 after she learned that she carries the same gene mutation.

Degen has blogged about the process, including posting pictures, to help other women through the process.

Degen says a celebrity speaking out will help inform women around the world about genetic testing and the available treatments.

“People don’t know about the gene, they don’t know about the preventive surgery,” Degen told CTV. “They think it’s drastic.”

In her piece, Jolie, an international sex symbol, wrote that she didn’t feel her surgery changed her as a woman.

"I do not feel any less of a woman," Jolie wrote. "I feel empowered that I made a strong choice that in no way diminishes my femininity."

With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip