Assisted suicide advocate Brittany Maynard took her own life on Saturday, just before her 30th birthday.

"Goodbye to all my dear friends and family that I love. Today is the day I have chosen to pass away with dignity in the face of my terminal illness, this terrible brain cancer that has taken so much from me...but would have taken so much more," she wrote on Facebook, People reports.

"The world is a beautiful place, travel has been my greatest teacher, my close friends and folks are the greatest givers. I even have a ring of support around my bed as I type...Goodbye world. Spread good energy. Pay it forward!"

Maynard was diagnosed with a brain tumour on January 1 this year. She was later told that she had just six months to live, and decided to end her life before her illness became too debilitating.

She moved to Oregon, one of just five states in the US where assisted dying is legal, and campaigned for dignity in dying in her last few months, becoming the face of advocacy organisation Compassion & Choices.

She also released a video on YouTube explaining her decision, which has now been seen over nine million times.

"After months of research, my family and I reached a heartbreaking conclusion: There is no treatment that would save my life, and the recommended treatments would have destroyed the time I had left," Maynard wrote in an op-ed for CNN.

"Having this choice at the end of my life has become incredibly important. It has given me a sense of peace during a tumultuous time that otherwise would be dominated by fear, uncertainty and pain.

"Now, I'm able to move forward in my remaining days or weeks I have on this beautiful Earth, to seek joy and love and to spend time traveling to outdoor wonders of nature with those I love...When my suffering becomes too great, I can say to all those I love, 'I love you; come be by my side, and come say goodbye as I pass into whatever's next.' I will die upstairs in my bedroom with my husband, mother, stepfather and best friend by my side and pass peacefully. I can't imagine trying to rob anyone else of that choice."

Maynard released a second video last week suggesting that she might delay her death because it didn't "feel like the right time".

However, a spokesperson for Compassion & Choices has confirmed that she died on Saturday, as she had previously decided, surrounded by her family,

"Brittany suffered increasingly frequent and longer seizures, severe head and neck pain, and stroke-like symptoms," a statement from the organisation reads.

"As symptoms grew more severe, she chose to abbreviate the dying process by taking the aid-in-dying medication she had received months ago. This choice is authorised under the Oregon Death With Dignity Act. She died as she intended – peacefully in her bedroom, in the arms of her loved ones."

Maynard's choice has sparked much debate about assisted suicide, particularly among Christians. Reverend 'Father Tony' Medeiros, of the Redemptoris Mater Seminary in Boston created a Facebook page encouraging believers to pray for her in the days leading up to her death.

"We are saddened to hear of the passing of Brittany Maynard, wife, daughter, and sister to all of us. As we prayed for her, loved her, and cared for her in life, so now let us pray for her in her death," a statement posted yesterday said.

"May God, our Almighty Father, forgive her all her sins and give her rest and peace in His presence in the Kingdom of his Son, where 'He will wipe away every tear from their eyes; and there will no longer be any death...no longer be any mourning, or crying, or pain' (Rev 21:4).

"Brittany we love you! Rest in Peace."