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1580s, "mistake, error;" 1610s, "misbehavior;" see miscarry + -age. Meaning "untimely delivery" is from 1660s. Miscarriage of justice is from 1875.
miscarriage mis·car·riage (mĭs'kār'ĭj, mĭs-kār'-)n. Premature expulsion of a nonviable fetus, especially before the middle of the second trimester of gestation; spontaneous abortion.
A spontaneous and premature expulsion of an embryo or fetus from the uterus before it is capable of surviving on its own.
Note: Generally, a miscarriage is a failure to achieve a desired end, as in a miscarriage of justice.