Thank you mlb. Very helpful.
Yes, it is just a blood draw on day 3 of your cycle. They test for lh, fsh, estriol, and a couple other things. It gives a general idea of your ovarian supply. Your progesterone could be low - but I just read this morning in an infertility specialists blog (http://infertilityblog.blogspot.com/) that usually low progesterone does not cause a miscarriage - rather a bad embryo will cause low progesterone. If yours is low, it is an easy fix with progesterone suppositories or injections. Good luck!