HOUSTON -- Former first lady Barbara Bush is in "failing health" and won't seek additional medical treatment, a Bush family spokesman said Sunday.

"Following a recent series of hospitalizations, and after consulting her family and doctors, Mrs. Bush, now age 92, has decided not to seek additional medical treatment and will instead focus on comfort care," spokesman Jim McGrath said in a news release.

McGrath did not elaborate as to the nature of Bush's health problems. She has been treated for decades for Graves' disease, which is a thyroid condition, had heart surgery in 2009 for a severe narrowing of her main heart valve and was hospitalized a year before that for surgery on a perforated ulcer.

"It will not surprise those who know her that Barbara Bush has been a rock in the face of her failing health, worrying not for herself -- thanks to her abiding faith -- but for others," McGrath said. "She is surrounded by a family she adores, and appreciates the many kind messages and especially the prayers she is receiving."

Bush, who is at home in Houston, is one of only two first ladies who was also the mother of a president. The other was Abigail Adams, wife of John Adams, the nation's second president, and mother of John Quincy Adams, the sixth president.

Bush married George H.W. Bush on Jan. 6, 1945. They had six children and have been married longer than any presidential couple in American history.

Eight years after she and her husband left the White House, Mrs. Bush stood with her husband as their son George W. was sworn in as the 43rd president.

She's known for her white hair and her triple-strand fake pearl necklace.

Her brown hair began to gray in the 1950s, while her 3-year-old daughter Pauline, known to her family as Robin, underwent treatment for leukemia and eventually died in October 1953. She later said dyed hair didn't look good on her and credited the color to the public's perception of her as "everybody's grandmother."

Her pearls sparked a national fashion trend when she wore them to her husband's inauguration in 1989. The pearls became synonymous with Bush, who later said she selected them to hide the wrinkles in her neck. The candid admission only bolstered her common sense and down-to-earth public image.

Her 93-year-old husband, the nation's 41st president who served from 1989 to 1993, also has had health issues in recent years. In April 2017, he was hospitalized in Houston for two weeks for a mild case of pneumonia and chronic bronchitis. He was hospitalized months earlier, also for pneumonia. He has a form of Parkinson's disease and uses a motorized scooter or a wheelchair for mobility.

Before being president, he served as a congressman, CIA director and Ronald Reagan's vice president.

Barbara Pierce Bush was born June 8, 1925, in Rye, New York. Her father was the publisher of McCall's and Redbook magazines. She and George H.W. Bush married when she was 19 and while he was a young naval aviator. After World War II, the Bushes moved to Texas where he went into the oil business.

Along with her memoirs, she's the author of "C. Fred's Story" and "Millie's Book," based on the lives of her dogs. Proceeds from the books benefited adult and family literacy programs. The Barbara Bush Foundation for Family Literacy began during her White House years with the goal of improving the lives of disadvantaged Americans by boosting literacy among parents and their children. The foundation partners with local programs and has awarded more than $40 million to create or expand more than 1,500 literacy programs nationwide.

By Michael Graczyk, Associated Press