I have the same experience--3 c-sections. I asked my doctor if I could weather a 4th and he told me a story about when he was in medical school he watched a woman bleed to death from uterine rupture. I guess it's one of those few things that happen during pregnancy where the survival rate for mom and baby is just about nil.
After that, my husband decided to have a vasectomy--my doctor said tubal ligations cause a host of hormonal problems for women. It was a very painful decision and I still wish we could have more children, but not at the risk of my children not having a mother.
My last child was conceived just six months after the previous section so my doctor was understandably worried. The incision hadn't even had time to really heal well.
Talk about one scared momma! Fear played a huge part in that, but gave birth to a wonderful kid..it was a difficult pregnancy though and the recovery was just awful.
There are times when you do have to listen to what medicine says.