While I view the modern approach--give the infant some anesthetic--as best, here is another thought about not being able to remember the pain afterwards (reportedly babies that were operated on without anesthesia have no memory of it, even years later).
I have had several colonoscopies, dating back 20 years or more. (Yes, I am that old, and get off my lawn.) For the first couple, I remember it as at best uncomfortable, and at times painful. But ten or so years ago, they started giving some kind of anesthesia. I've heard that you're not really unconscious from this, and from what I've been able to squeeze out of the doctors and anesthesiologists, it sounds like you still feel some pain. But I (and apparently other patients) have absolutely no memory of that; I can recall getting the IV and being told to lay on my side, and that's all until I woke up in recovery. And the odd thing about that is, I'm perfectly ok with it. I don't go into colonoscopies now dreading the discomfort, and I don't worry afterwards that I might have been in pain. I don't understand it, but There It Is.