Progesterone Therapy Entire Pregnancy Safe

I am 13 weeks and have been taking 200mg progesterone suppositories 2x/day since I found out I was pregnant. I had two miscarriages last year and I also found out that my current pregnancy is high risk due to placental problems. So naturally I'm terrified of going off the progesterone as one usually does after the first trimester. Any of you (or anyone you know of) has similar issues and stayed on progesterone the entire pregnancy? Ideally I'd like to wean to a smaller dose and get my blood drawn periodically to make sure everything is still okay