Now, I don't have kids... so take this with a grain of salt.
Parenthood isn't about what YOU want. It's about what's best for your child. My experience is all with my nephews, and they were great when they were younger... but I wasn't the one losing sleep to care for them. I didn't have any of the medical costs associated with raising them, or other costs... clothing, food, etc. Now they are teenagers/young adults they are horrible. I mean I love them... but they treat their parents like crap. It's expected... think about yourself as a teenager.
I like being an aunt better than being a mom, I get to leave. Callie is right... you are going to want a break from it. You'll want them to be cursing out some one else and not you. (tough luck, they'll do it to both of you) At some point, you're going to want to say, "go ask your father" because they'll bother you to the point of breaking. They'll test you on everything. They might get hurt, and they'll definitely get sick. You'll want some one to lean on that understands what you're feeling when that happens. Some one to balance you out, so you know you're making the best decisions possible.
It's possible he will sign over parental rights to you if you talk about it ahead of time. (that also means no child support) But to just not tell him, unless he's a seriously horrible human being, I feel like that's a terrible thing to do. And if he is a horrible human being, why are you with him/why are you wanting to have his kid?
It's your life, until you have kids.