Jimmy Carter was preparing to celebrate his 100th birthday on Tuesday, the first time an American president has lived a full century and the latest milestone in a life that took the son of a Depression-era farmer to the White House and across the world as a Nobel Peace Prize-winning humanitarian and advocate for democracy.

Living the last 19 months in home hospice care in Plains, the Georgia Democrat and 39th president has continued to defy expectations, just as he did with his rise from his family peanut farming and warehouse business to the world stage.

He served one presidential term from 1977 to 1981 and then worked more than four decades leading The Carter Centre, which he and his wife Rosalynn co-founded in 1982 to “wage peace, fight disease, and build hope”.

“Not everybody gets 100 years on this earth, and when somebody does, and when they use that time to do so much good for so many people, it’s worth celebrating,” Jason Carter, the former president’s grandson and chair of The Carter Centre governing board, said in an interview.

“These last few months, 19 months, now that he’s been in hospice, it’s been a chance for our family to reflect,” he said.

“And then for the rest of the country and the world to really reflect on him. That’s been a really gratifying time.”

The former president was born on October 1 1924 in Plains, Georgia, where he has lived more than 80 of his 100 years.

He is expected to mark his birthday in the same one-storey home he and Rosalynn built in the early 1960s — before his first election to the Georgia state Senate.

The former first lady, who was also born in Plains, died last November at 96.

The Carter Centre hosted a musical gala in Atlanta in September to celebrate the former president with a range of genres and artists, including some who campaigned with him in 1976.

The event raised more than 1.2 million US dollars (£900,000) for the centre’s programmes and will be broadcast on Tuesday on Georgia Public Broadcasting.

Mr Carter survived a cancer diagnosis at age 90, then several falls and a hip replacement in his mid-90s before announcing at 98 that he would enter hospice care.

Townspeople in Plains planned another concert on Tuesday evening.

The last time Mr Carter was seen publicly was nearly a year ago, using a reclining wheelchair to attend his wife’s two funeral services.

Visibly diminished and silent, he was joined on the front row of Glenn Memorial United Methodist Church in Atlanta by the couple’s four children, every living former first lady, President Joe Biden and his wife Jill and former president Bill Clinton.

Jason Carter said the centenarian president, born four years after women were granted the constitutional right to vote and four decades before black women won ballot access, was eager to cast his 2024 presidential ballot — for Vice President Kamala Harris, the Democrat who wants to become the first woman, second black person and first person of south Asian descent to reach the Oval Office.