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Former first lady Nancy Reagan  has been recovering from several broken ribs incurred a fall in her California home six weeks ago.

The accident didn't become public until  Tuesday night, however, when  Reagan canceled a personal appearance at a speech by Republican Rep.  Paul Ryan at the Reagan Presidential Library in Simi Valley. The director of the Reagan Library announced that  the former first lady was at home recuperating from a fall.

"Falls in someone this age can be very serious. They are one of the leading causes of death," says Dr. Richard Besser, chief health and medical editor at ABC News. "A broken rib makes it hard to take a deep breath, and that can set you up for pneumonia, which in the elderly, in particular, can be deadly."

Last summer, the former first lady lost her balance at  the Reagan Library   but Sen. Marco Rubio, R-Fla.,  saved her from hitting the floor. In 2009, Reagan broke her pelvis in a fall.

As the widow of Ronald Reagan, Nancy Reagan, now 90 years old,  is a revered figure in the Republican Party. Her last public appearance was at a GOP primary debate last September at the presidential library, where the candidates gave her a standing ovation.

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