it relaxes crampy muscles that may be preventing the egg from moving along. Apparently sometimes it does work. Also, I can tell you that Matilda *really* liked it (although it did not in fact fix her eggbound problem)... I think she was in pain and the warm sitzbath made her feel better. Which aside from making it easier for an egg to pass, should count for *something* in and of itself, I think.
Pat
Pat