A miscarriage is the spontaneous loss of a pregnancy before 23-24 weeks of pregnancy, before the fetus becomes viable.
The medical term of miscarriage is a "spontaneous abortion".
Studies have shown that a miscarriage happens in about 60% of all pregnancies, and most of these happen before the pregnancy is clinically recognized.
After a pregnancy is clinically recognised about 25% of pregnancies end in a miscarriage.