Quoting Gemmas mommy!:" Don't abort your baby just because he wants you to, you will regret it for the rest of your life."
My fiance tried to convince me to abort early on, but I stood my ground because it wasn't something I wanted to do even though it was unplanned. He eventually changed his mind and is glad we're having her.
If you terminate, make sure it's because you feel it's the right thing to do. Other wise you'll resent him forever for pushing you into it. I know I would have never forgiven my fiance had I gone through with it.
Whatever you decide, best of luck.