Progesterone during pregnancy

I had a silent MC last Nov. at 10 wks.  I am 37 and am now pregnant again. My HCG level & Progesterone levels were "perfect", but my Dr wants me to take a progesterone vaginal suppository called Crinone anyway-just in case. After my last MC I am hesitant to take any medicine unless absolutely necessary.  By the way my twin sister just gave birth to a healthy baby boy last June.  What are your opinions or experience with this?