"Abortion is the spontaneous or induced termination of pregnancy before fetal viability. Because popular use of the word abortion implies a deliberate pregnancy termination, some prefer the word miscarriage to refer to spontaneous fetal loss before viability [...] The National Center for Health Statistics, the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO) define abortion as pregnancy termination prior to 20 weeks' gestation or a fetus born weighing less than 500 g. Despite this, definitions vary widely according to state laws."