原本
There is no any direct simptom or causes. It can happen to any women when they have a sex. Mostly. When sex happen, there is a sperm thats not succesful to become a fetus. Let say there is a Y & X kromosom, it should be the same... But sometimes can happen like xx+xx...this can be the molar. But not 100% yes...thats why we can't confirm what it is cause...