I had two pregnancies that resulted in healthy babies followed by a MMC and 2 chemicals in a row, i finally have my answer so sharing in case it helps someone else. I did a full RPL panel and everything was normal but 1 test, my endometrial biopsy results came in as positive for chronic endometritis (note- this is NOT the same as endometriosis, totally different). Basically some bacteria got into my uterus causing inflammation and this is making my pregnancies fail. Treatment is a two week course of antibiotics followed by a repeat biopsy to make sure it’s all cleared. The biopsy results take a long time to come back so it will be a few months before I can try again. It’s super frustrating to have so many months spent on this process (2 months waiting for first appointment, 2 months to do preliminary testing, 2 months to treat and retest) but I’m relieved that I can maybe prevent another loss.