Had 2 missed misscariges both died at 8 weeks what are the causes and how can I prevent it happening again had healthy babies before?

MFM. You need a consultation with maternal-fetal medicine specialist to help you find the answer to that question, and you need to do it before conception. There could be something wrong with you that is causing habitual miscarriage or there could be something genetically wrong that creates a fetus with a problem. These are the things that the MFM specialist will help you explore.