Was just prescribed Prochieve

Hello, I'm 25, and I'm 5 weeks into my very first pregnancy. I've never had a miscarriage, however, when I had my second blood draw yesterday they told me that the porgesteron level dropped 2 points and that it wasn't bad. But my doctor wants me to start on Prochieve. Aside from is being expensive, isn't it a little early to put me on something that is most often prescibed to women who have had multiple miscarriages before? I really don't want to take it, especially since it says in the letter that comes with it that birth defects have been reported! Abdominal Wall defect and cleft palate! Is there anyone else that has NOT had a miscarriage before and was prescribed this?
Please help.....

Lisa