Is to much progesterone bad??

My blood work came back as normal progesterone level. But before I took my blood work my doctor proscribed me progesterone. Because I had 2 miscarriages in the past. My question. Is should I still take it even tho my blood work came back normal for progesterone ?  
I know is to help the placenta but is too much pregensterone bad. If I keep taking it ?