CNN reported that Bush was suffering from chronic obstructive pulmonary disease and congestive heart failure. That may be because the 92-year-old former first lady has faced it before, in the hardest way imaginable. She formed the Barbara Bush Foundation for Family Literacy to fund programs that teach parents in low-income families to read and pass on a love of reading to their children.
Before serving as first lady, she served as second lady from 1981 to 1989.
Their son, George W Bush, was elected president in 2000 and served two terms as the nation's 43rd president.
Bush had an independent streak and could be sharp-tongued.
She discouraged speculation that she wielded political influence with the president like her predecessors - Ronald Reagan's wife, Nancy Reagan, and Jimmy Carter's wife, Rosalynn Carter.
Bush said she did her best to keep her opinions from the public while her husband was in office.
Husband George, the nation's 41st president, is now 93 years old and struggling with a Parkinson's-like disease that forces him to use a wheelchair and makes it hard for him to speak.
With hair that had turned white prematurely, Mrs Bush was known by family members as the "Silver Fox".
Bush is survived by her husband; five children George W., Neil, Marvin, Jeb, and Dorothy; 17 grandchildren; seven great-grandchildren; and her brother, Scott Pierce.
In 1953, soon after George H.W. Bush had moved his family to Midland, Tex., to get into the oil business, the couple's 3-year-old daughter complained about feeling exhausted. When the Bushes moved into the White House, Gigi and her father were invited to a state dinner.
Sons George and Jeb have also visited in the past week.
In 1984, her quick wit got her into trouble when she was quoted as referring to Geraldine Ferraro, the Democratic vice presidential nominee at the time, as "that $4 million - I can't say it, but it rhymes with rich".
He said his mother was able to enjoy one of her favorite past times: reading.
"She's never shied away from saying what she thinks".
"We were rambunctious a lot, pretty independent-minded kids, and, you know, she had her hands".
Details about a public viewing for Mrs.
"I wish him well", she said.
Her uncoiffed, matronly appearance often provoked jokes that she looked more like the boyish president's mother than his wife. "That's because I'm everyone's grandma".
Bush was born in 1925 in New York City, but was raised in Westchester County. "Her dedicated service to the American people was matched only by her compassion and love of family". She dropped out of prestigious Smith College to marry Bush, then a young naval aviator home on leave from World War Two.
In a statement, Bill and Hillary Clinton said Mrs Bush was "feisty in support of her family and friends, her country and her causes". While they were engaged, his bomber was shot down by the Japanese in the Pacific in 1944.
"You have given me joy that few men know", he wrote. "He was Superman", she told CNN in 2003.
"That started my cure", she wrote in her memoir.
A writer, her books include an autobiography and one about post-White House life.