One of my friends who has four children asked me if it's possible for epidurals to become less effective because of becoming tolerant of the medicines in the epidural as hers had become less effective with each birth. I did not know the answer. So at one of my prenatal appointments I asked my doctor about this.
My doctor said that this is not really possible because of the way epidurals work. An epidural is a temporary block on the nerves that is there and then goes away. There is not a way to build up the medicine because it is not metabolized like medicines that you ingest. He said that it could be possible if you were given epidurals every day, but this is not likely for women having babies.
Why then were the epidurals less effective each time? I have no idea and neither did my doctor.
Have you had the experience of epidurals being less effective with each delivery?