Both stillbirth and miscarriage are types of pregnancy loss, but they differ by when the loss occurs. A miscarriage (sometimes called a spontaneous abortion) is when a baby dies before the 20th week of pregnancy. Stillbirth is the death of a baby after the 20th week of pregnancy but before delivery. Researchers estimate that, among women who already know they are pregnant, nearly 15 percent will have a miscarriage.Stillbirth can occur before delivery, or as a result of complications during labor and delivery. In at least half of all cases, researchers can find no cause for the pregnancy loss. In spite of how often stillbirth occurs, and how emotionally painful it can be, little research has been done on this type of pregnancy loss