I hear a lot of birth stories from mom's and I hear a lot of stories from women who have complained of horrific back labor. Most people don't know what causes back labor and the simple things they can do to avoid it.
Back labor is caused the majority of the time by a malpositioned baby. This technical term is Occiput Posterior (OP). This means that the back of the baby's head is against mom's back. What really causes the discomfort associated with this is that it is like bone rubbing against bone.
The following is an article about posterior positioning and some things that can be done to prevent/correct it.
There is an awesome website that talks about Optimal Fetal Positioning called www.spinningbabies.com.
Posterior babies are something that didn't really happen 30, 40 or 50 years ago or even before that. I'm sure it happened but it is something that has become more and more prevalent.
Some of the reasoning as to why the huge increase is that we've become a couch potato society. If you consider that the back of the baby's head is the heaviest part what do you think happens when you plop down in the recliner with the remote? Gravity spins the baby around so that the back of his/her head is towards your back. Some great pointers are to stay upright, spend some time doing a hands-knee position or knee chest postion daily. If you have a good prenatal yoga class nearby take it. Chiropractic is great because it keeps the pelvis in good alignment and gives the baby the maximum amount of space to turn in. As with everything prevention certainly work better than trying to "cure" the problem once in labor.