My dear Anonymous,
This is certainly a difficult situation, but I encourage you to be honest with yourself and your parents.
I can't precisely script what you should say to them, but I'm sure you can find a way to talk to them in a calm, rational manner and tell them both about your pregnancy and your concerns about their reactions.
Don't Accuse; Relate Your Fears
You should try to let them know in such a way that they won't be put on the defensive. Don't accuse them, for instance, of rejecting you. Rather, note your fears and, if applicable, why you were concerned. You don't mention whether you have valid reasons for thinking your parents will reject you (i.e., past experience).
The Plusses of Your Situation
The facts that you're in college AND with the father of the baby are definitely plusses. If you believe you can be a good parent and can support your child, all these things should work in your favor.
Conquer Your Fear
All in all, I fully believe that open, honest communication is essential here, and I encourage you to conquer your fear and face the world and your future with confidence!