Fay,
 I used dex with my second pregnancy.  It turned out that I was carrying an affected girl.  I was so pleased with the way things turned out for us.  She was born with no virilization and I had no side effects.  I have heard other mothers though that did not have the same wonderful experience that I did.  Some of the side effects that I know of are high blood pressure, stretch marks that are worse than normal, irritability and nausea.  Now, I did try to argue with my husband that the irritability I experienced was a result of the dex but he pointed out that I was just as irritable with my first pregnancy.    :)  I would think the blood pressure issue would also depend on if you already have a history of high blood pressure.  My blood pressure has always been low.  It’s usually 80 or 90 over 50 or 60.  My "dex" daughter actually weighed a few ounces less than my first daughter and they were both full term babies.  I am not sure and have not heard if dex causes the babies to weigh more at birth.  In my case, it had no bearing.
Fay, there are so many thoughts and opinions on dex treatment during pregnancy.  I think it is smart to do your research and choose the route that makes you the most comfortable.  We went through a very scary birth with my first daughter and she was severely virilized.  It felt so incredible to me to be able to prevent that from happening in my second daughter.  Plus, since she was already diagnosed, we were able to carefully coordinate her birth with all of the specialists and it made things a bit more normal for us.  I would do it again in a heart beat!  But I have read other mother’s stories and can see why they would never want to do it again.  Dr. New and Dr. Pang have both studied dex treatment extensively.  I bet their websites would have great information for you.
Best wishes!
Tonia