Much of these maternal deaths were due to puerperal fever, then known as childbed fever. She died from childbed fever after giving birth to Wanrong. The particles were resorbed, and childbed fever resulted. Thus, Semmelweis concluded some unknown "cadaverous material" caused childbed fever. His wife, Herta Probst, was sick with childbed fever at the time. Seven weeks later on December 29, 1879, May died, possibly of childbed fever. He wished to show that childbed fever was related to pathological anatomy. In this way they become carriers of the decaying matter responsible for childbed fever. But this was only one of many possible causes for childbed fever. He turned every conversation to the topic of childbed fever. One night Morella's spirit rises, and kills Lenora in revenge for her childbed death. He published a book of his findings in "Etiology, Concept and Prophylaxis of Childbed Fever".