I started this board when I was pregnant with twins (one year ago!!) because there were no twins/multiples boards. However, after the girls were born, I had no time to hop online.
I delivered my twins 2.5 months early. Eva was 2 pounds 13 oz delivered vaginally, her sister Autumn was 3 pounds 1 oz delivered c-section 31 minutes later. They were in the NICU for 6 weeks and left when they were 5 pounds 10 oz. They were SO healthy compared to the rest of the babies there, and caught up in growth at around 7 months old. They will be 1 year old May 16th, 2011!! They are standing and starting to try to balance without support, and they can walk if you hold their hands. It is likely your twins will be born early, though hopefully not as early as mine! I think they only were early because Eva went into distress - I think her sac had ruptured because I was leaking the night before - didn't think it was her water breaking though. It was a very close call - the doctor didn't believe that 4/5 symptoms of pre-term labor were cause for concern, so I didn't go in until about an hour before Eva was born. She was crowning by the time they did a cervix check.
Please, if you think there is an issue, GO TO THE EMERGENCY ROOM! Doctors are not infallible, and ones you trust can be just as lazy as anyone else (my doctor was on call and she was the one who said it was nothing - I think she didn't want to have to take the time to see me). I and my girls were very blessed, and I hope your pregnancy goes as smooth as mine did MINUS the pre-term labor.

(Really, I had no serious issues during my pregnancy up until the girls were born).