When people ask me what labor and childbirth were like, I invariably give the same response: imagine the most horrible menstrual cramps you've had and multiply that by 1,000. Then imagine that stabbing feeling you get in your bowels when you seriously have to poop and multiply that by 1,000. Now let that go on for 18 hours. That's about right. Of course, pain is relative and every person, every body and everyone's pain tolerance is different, so when women describe what a contraction feels like it can differ considerably from person to person. (That said, I have never personally encountered anyone who has told me it feels like butterflies and rainbows cheerfully co-mingling inside of them, so some things are just straight-up universal.)
Pregnant women have months to get themselves used to the idea of labor. Many (myself included) will reach a certain point in their pregnancy and start sobbing because they just want to be done and it all to be over with. They'll try everything they can to try to induce labor, thinking, "I need to meet this baby, besides, nothing can be worse than feeling pregnant for another godforsaken minute." Then the contractions start. Usually, they start off relatively gently and seem completely manageable but, inevitably, there comes a point where many a loving and dedicate mom-to-be will think to herself, "I've changed my mind. I'd rather be pregnant forever." (This feeling usually goes away once you finally see your little one. That's pretty great, too.)
Look, I don't want to scare you, but it's intense. Usually it's tremendously physically intense, but just the fact that you know you're bringing a new human into the world can be pretty heavy all the way around. As I said, everyone experiences labor and contractions differently, so I talked to other moms who have been there and done that, to see what things were like for them.