A miscarriage is characterized by the loss of a fetus before 20 weeks of pregnancy. This usually happens within the first trimester of pregnancy. They can be of many types. They could be complete or incomplete, depending on the expulsion of tissues from the body, sometimes they can be caused by infections and there might be many other causes. Vanishing twin syndrome is a lesser-known kind of miscarriage. In this kind of baby loss, you might be told earlier that you are carrying twins but later during a routine screening, only one fetus is detected.