I don’t think they did, the concept babies didn’t feel pain persisted well into the 1980s.

In the late nineteenth, and first half of the twentieth century[citation needed], doctors were taught that babies did not experience pain, and were treating their young patients accordingly. From needle sticks to tonsillectomies to heart operations were done with no anaesthesia or analgesia, other than muscle relaxation for the surgery.[citation needed] The belief was that in babies the expression of pain was reflexive and, owing to the immaturity of the infant brain, the pain could not really matter.[37]