Betty White died from a stroke she had six days before her Dec. 31 death at age 99, according to her death certificate.

Betty White was America’s naughty sweetheart.

A new coffee table book celebrates Betty White's life and career as she nears 100.

FILE - Actress Betty White poses for a portrait in Los Angeles on June 9, 2010. (AP Photo/Matt Sayles, File)LOS ANGELES – True to form, Betty White has something impish to say about her birthday Sunday. “Since I am turning 99, I can stay up as late as I want without asking permission!” she told The Associated Press in an email. Her birthday meal will be a hot dog and French fries brought in — along with a bouquet of roses — by her longtime friend and agent, Jeff Witjas. In January alone, White is on screen in reruns including “The Golden Girls” and “Hot in Cleveland”; the 2009 Sandra Bullock movie “The Proposal,” and the 2018 documentary “Betty White: First Lady of Television,” about her life and career.