As late as the 1950s, a Catholic theologian wrote that it was wrong to anesthetize pain, particularly in the sinner. It might interfere with his penance.
Up until the 1970s, babies often weren't given anesthetic even for procedures as traumatic as amputation. Doctors didn't believe that babies really felt pain.
* Quick facts from interview with Joanna Bourke, author of The Story of Pain: From Prayer to Painkillers, on the BBC's Start the Week.