Answer:
Well, Mary was weak and ill from May 1558. In pain, possibly from ovarian cysts or uterine cancer, she died on 17 November 1558, aged 42, at St James's Palace, during an influenza epidemic that also claimed the life of Reginald Pole later the same day. She was succeeded by her half-sister Elizabeth. And she died of Reproductive system disease. Hope That helps!
From Itsbrazts.
