Decisions like these are never easy to make. Definitely take the time to discuss things with the school's counselor, teachers, and other mentors in your life for advice.
I understand that everyone has different beliefs and feelings about abortion, but if I were in your place abortion would not even be an option. I am not in your place, but agree with the many other posts that anything is possible, even having to make it through nursing school while being pregnant can be done. You always have the option of adoption if you think you definitely wont have the time or will to be a good parent.
I am an A and B student who has three quarters left to go. I also have four children all under the age of twelve who my family and I home-school, so trust me, I know what difficult is!
Yes, I made the decision to put myself through the rigors of nursing school knowing that I had many responsibilities at home, but you also, being a nursing student, made the decision to have intercourse, which resulted in a pregnancy. Granted, you haven't given specifics of your whole situation, which you shouldn't have to, but I think you know what I am trying to say. Hopefully your pregnancy isn't the result of anything other than consensual sex.
I don't think you will regret it if you decide to go through with your pregnancy, even if you are a nursing student. Just take responsibility for your actions, which includes not taking the easy way out with an abortion.
I understand that many others have different opinions, and I have given mine.
No matter what, I know you have the strength inside of you to deal with whatever life brings you!