It's just a poetic turn of phrase meaning that Jesus' birth did his mother no harm, without getting into the nitty-gritty details of labor and delivery.
Since I have known plenty of moms who gave birth with no anesthesia and very little pain (my own mom and my self among them, mom being one of the first generation of American followers of Grantley Dick-Read M.D.), I would expect that the Blessed Mother's 'childbirth experience' would be at least that good, and better.
Oh, that kind of thing always throws me off.
My wife is 4'11" and 95 pounds. She has given birth five separate times and never had anaesthetic during any of those births. Of course, I always made sure that her nails were clipped short...