Hi,
They will probably test you for thyroid problems, polycystic Ovaries, undisclosed diabetes and the blood clotting disorder Antiphospholipid Syndrome which is a common cause of recurrent miscarriages (i have this).
They will also probably look at you and your DH's chromosomes to check either of you aren't carrying a chromosomal defect called a ?balanced translocation?. (this is a rarer cause of recurrent miscarriages)
They probably won't check for incompetent cervix, or abnormally shaped cervix problems such as a ?bicornuate? uterus or a ?unicornuate? uterus because these tend to cause second trimester miscarriages and your dates are significantly earlier than this.
Again, they probably won't check for inherited clotting disorders called
?thrombophilias? like factor V Leiden, factor II (prothrombin), gene
mutation and protein S because these also tend to cause second trimester miscarriages.
(Obviously this is all affected by your medical history, from this they might have a reason to suspect the cause is for example thrombophilia after all if there is a significant family history) so it is not set in stone.
The only thing they might not test for, but i'd be tempted to look into, is something called natural killer cells. This is quite contraversial- not all clinics believe in them or consider them. But those that do pinpoint them as a major factor in early losses.
If my losses were all in the first trimester and there was nothing else coming back from the tests, I'd personally want to rule it in/out.
I don't know a lot about it as I'm definitely clotting problems, but if you look for the thread about trying to conceive on prednisone, (which is the treatment prescribed for this if diagnosed) I'm sure the lovely ladies on that thread can give you lots of useful info about it.
I would also suggest you get hold of the book "'Miscarriage: What every Woman needs to know' by Lesley Regan ". You can get it cheaply of Amazon and it has a lot of good info in it. (She is the head of the recurrent miscarriage clinic at St Mary's in London which is considered a centre for excellence throughout europe).
Good luck, and stay in touch- we can compare notes x