I have run only 2 marathons and I didn't hurt in either one because I was well trained. Yes, I was tired in the last 10k but not in pain. I have given birth to 4 kids with NO medication or pain relief. Two were even born at home. No childbirth is the same. My first one was pretty bad mainly because I had back labor and I had NO idea how much pain I could go through and still live. My 2nd one hurt a lot but not as bad as the first. My 3rd was fast and furious and I had no relief between contractions, definitely my most painful. And my 4th was almost pain free, only some mild cramps and didn't realize how far along I was (I had been out jog/walking a 2 mile loop in the neighborhood). I ended up delivering my baby on the bathroom floor only 10 minutes after coming home. She was 9lbs and 22 inches long and, I guess God took pity on me because it did NOT hurt. So....my vote is that child birth is much more painful than a marathon when compared to my first 3 labor and deliveries. I remember running out at Kennesaw Mountain State Park during my first pregnancy and I would end a lot of my runs up this very steep hill to a parking lot. I told myself that this "pain" would prepare me for childbirth pain. Ha! Nothing can prepare you for that!