Have you had immunology testing? X
I highly recommend testing the embryos. I had 2 early miscarriages before ivf. Most of the embryos we were able to create were not PGT-A normal, which, if transferred, would've most likely ended in a miscarriage. We transferred our first PGT-A normal embryo, ot stuck, and is now my 5 month old daughter.
We had a natural miscarriage than struggled to convince again so done IVF as I was approaching 40 and didn't feel time was on our side. Our first round we didn't test and had 4 embryos at day 5. We didn't test as we had no diagnosis of why it wasn't working and the cost! From that round we'd 2 fails 1 miscarriage and 1 didn't survive the thaw. Then I read the book It starts with an egg - I highly HIGHLY recommend this!! After taking supplements for about 8 weeks We did another round and had 4 normal embryos and now have 2 little ones and 2 on ice. Definitely recommend testing and reading the book!
If the miscarriage were during the first trimester it is highly likely that the embryos were not genetically correct. When there is recurring miscarriage it is recommended to do PGT A on the embryos to be sure that the one you transfer is normal. If they can't find any other reason for the miscarriages, the best option would be to do PGT a. That is my opinion as an embryologist