Final answer:
Miscarriage is the natural loss of a fetus before 20 weeks of gestation, often due to developmental problems that prevent the fetus from growing properly.
Step-by-step explanation:
Miscarriage, also known as spontaneous abortion, is a natural occurring loss of a fetus prior to 20 weeks of gestation. This often happens because the fetus cannot develop properly, leading to its natural termination. A fetus, considered a prenatal human being, reaches a stage from week 9 after fertilization to about 38 weeks of gestation, where it becomes viable with possible chances to survive outside the uterus. Fetal viability is a term that is closely linked with the legal and moral discussions surrounding abortion and contraception as states consider different gestational ages as to when the procedure may be allowed or prohibited.