As of three years ago when I was pregnant there were no available studies that indicated any side effects of taking Dex that I know of.  I know that my son’s Endo was definately not an advocate of taking Dex.  Reason being that there is a 1 in 8 chance of having a girl with CAH.  She also was concerned that there were not any studies to tell us what effect if any taking Dex has on a baby other than that of a girl with CAH.

I however did opt for the Dex against her advice.  I was on the Dex for about 12 weeks until we learned that my daughter does not have CAH, but my son does.

It is one of those decisions that is very difficult.  Ask your doctor to give you a copy of the studies they are taking about.  Even go for a second opinion.  All I can suggest is that you need to research the Dex.  It is your body, your baby, your decision to make!  Good luck and enjoy your pregnancy!!!