There is a whole work up they do. I have recurrent m/c (just diagnosed), but already had two kids first...go figure! My OB was absolutely great about it, saying that even after 3 in a row, there is still a very high chance (like 70%)...that you will become PG with no treatment at all! Not saying that you shouldn't get treatment, but, it does sound good, doesn't it? And apparently (this is just what my OB told me) that your chances of m/c, never go higher than 30%, even after more than 3 in a row.
As far as testing...they gave me blood work up, an HSG, and I am waiting for an endometrial biopsy in August (testing hormones???). There are other tests too...but, they have to do with genetics, and your body trying to fight off the pregnancy (wich apprently is easy to fix...baby asprin!). I am not getting these tests done since it is unlikely they apply to me since I have already had two kids (with the same man). So, it really is good to get the tests done, get it all checked out....and if there is something, then get that taken care of.
The good news is your body knows what to do as far as you getting pregnant and putting it in the right place (your uterus and not your fallopian tubes, etc)...doesn't make it any easier to lose your baby tho. I know how much it hurts...I still hurt and my last m/c was in December. The ladies here are very supportive, and I have done most of my mourning for my wee ones on this site.
Hugs to you, and keep us updated on your appointment.