I've had 2 children, and the first one was significantly more painful. I moaned and groaned with the second one mainly to get some extra back and neck rubs, and that child weighed 2 pounds more than the first one!
My first one... the contractions were pretty bad once they got started. I had a very quick and intense labor, especially for a first birth. They would rise up and hold and then fall away, only to start tightening again before I could get a breath in. They were relentless and that was the worst part - no rest. They gave me an oxygen mask but I had to push it off because I couldn't get deep enough breaths with it. I could not speak through the contractions - they feel like an extremely intense gas buildup - but I didn't scream or yell. It's not really my personality, though. I would say that was the most pain I'd felt in my life... a 9, maybe. But I knew what it was for, so it was ok. I closed my eyes and hummed with each breath through them... it was what helped me the most, hearing the steady tone of my voice rather than the clattering and other people talking. It helped me focus. I felt very alone during that time, realizing that I was the only one who could finish the job, no matter what.
The first birth is also the hardest because you have to learn to push the baby out. It was something that took practice to do effectively. By that time I had an epidural, so it didn't hurt nearly as much. Epidurals are like heaven, by the way. Like getting your tormented lower half dowsed with a cool waterfall... and then nothing.
Still, pushing seemed so hard, like I wasn't getting anywhere. I felt very tired and scared that my pelvis might crack or something from the pressure. But when my husband said 'You're almost there', I knew I was only seconds away, because I knew he meant it literally, not like the doctor who'd been saying it for the past 2 hours. And then I was a mother. The pain/pressure dissipates immediately. It's surreal.
The thing I was NOT prepared for was the huge jello-like blood clots that get pushed out of you for the next few hours!! (Contractions continue for some time after the baby comes out). They were like... the size of my fist...I thought I was dying lol~!!
The second baby, I knew what I was doing. I knew when to ask for the epidural. I knew how to push. I wasn't as scared. It was so much easier, I would say pain was a.. gosh... a 3... less painful than having indigestion. Really.
Maybe TMI! But that's my experience in a nutshell! The pain was short lived, and very much worth it to have met the 2 most delightful people in my life.