The Hungarian obstetrician Ignaz Semmelweis, born 200 years ago this month, saved the lives of hundreds, possibly thousands, of new mothers with his forward-looking ideas about hospital hygiene. He insisted that junior doctors working for him wash their hands in chlorinated lime solution before examining expectant mothers. This simple procedure reduced mortality by something like 90 per cent at the Vienna maternity ward that he was in charge of. Many more deaths could have been prevented had other physicians followed his advice without delay. So why did many in the medical profession resist not just Semmelweis's findings but also similar ideas of his fellow hygiene pioneers, such as Joseph Lister? Quentin Cooper discusses the beginnings of surgical cleanliness with Dr. Sonia Horn from Vienna University, Dr. Andrew Cunningham from Cambridge University and Prof. Michael Worboys from the University of Manchester. Photo: presurgery sanitization. (PeopleImages/Getty Images)