There are way too many factors involved and variables to consider to give a clear cut answer to this.
Hi no its not always to do with progesterone problems,some times its due to abnormal chromozones,unhealthy egg,there are many reasons for it happening,if you have suffered several mc,they can begin tests,to determine the cause,but sadley its a very common thing.i had a missed mc many many years ago,i didnt bleed at all the egg just dissolves within the body,this is usually the case in very very early pregnancy,mc are normally when a bit further on,hence you pass tissue,or clots..