DefinitionA miscarriage is the spontaneous loss of a fetus before the 20th week of pregnancy. (Pregnancy losses after the 20th week are called preterm deliveries.)A miscarriage may also be called a "spontaneous abortion." This refers to naturally occurring events, not medical abortions or surgical abortions.Other terms for the early loss of pregnancy include:Complete abortion: All of the products of conception exit the bodyIncomplete abortion: Only some of the products of conception exit the bodyInevitable abortion: The symptoms cannot be stopped, and a miscarriage will happenInfected abortion: The lining of the womb, or uterus, and any remaining products of conception become infectedMissed abortion: The pregnancy is lost and the products of conception do not exit the bodySee also: Threate