What is the medical reason child birth is so painful? by Connie b. Dellobuono

Answer by Connie b. Dellobuono:

The expulsion of the fetus out from our body involves pain. With my first born facing posteriorly, I feel that a big piece of rock is trying to come out of me for 3 hours while I was on hands and knees. The pain for the second birth is like a knife cutting thru my opening as my baby comes out within 30 minutes, for which I have a tear in my perineum as a result. Labor cramps is part of the process. Our body allows rest in the between where we can gather our energy and breath deeply to allow labor to happen.

What is the medical reason child birth is so painful?