Often our dreams are about things that we see as threats, maybe your dream is just trying to understand all of the possibilities and prepare your subconscious for unwanted events. Not saying that its going to happen, but if its something you obsess over, its more than likely to manifest in your dreams.
Perhaps a significant change in your life is coming up
maybe that's how you feel right now, but feelings can and do change, especially if the right person comes along; and dreams about giving birth could also signify you giving way to some creative outlet; a new you being re-born.
It could mean many things, depending upon your life's circumstances. Pregnancy in dreams doesn't always relate just to having children. It could also be related to some aspiration you have regarding your school-work or career, or some other project that you're working on that you hope will work out very well for you.
Do you have any big class projects, or some kind of performance that you're preparing for right now?
Was last semester your first at college, have you recently switched majors, have you started thinking about graduate school?
There it is. The pregnancy symbolizes the (very natural) anxiety that you're feeling about the process of finishing high-school and applying to colleges. That's a perfectly normal dream for a woman your age to have.
DEEP DOWN.. YOU DO WANT KIDS. ADMIT IT.