Reproductive immunology

Hello,
I’m wondering if I’ve come to the right place – Valley IFV suggested you might be able to help. I’m looking for an immunology work up as related to recurrent miscarriages
(1 natural/successful pregnancy, followed by 3 miscarriages (natural pregnancies), and 1 miscarriage from IVF)
Saline sonograms, etc all clear. Looking for any additional immunology testing that might make sense before proceeding with another transfer (adding baby aspirin)

Many thanks!