Has anybody had more then 3 miscarriages and the doctor's don't know why?

Im sorry to hear that. I've had two, one at 7wks and one at 23wks, Drs don't have answer for me so i've been ttc for over a year now, I may have a weak uterus but all other tests have been good so idk, ill ask the dr to check that out for me and good luck