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When does an embryo become known as a fetus in human development?
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prenatal development
An ultrasound image of a human fetus.
In human prenatal development, the embryonic stage concludes at the end of the second month, when the developing organism is approximately 30 mm (1.2 inches) in length. From this point until birth, the term fetus is used to describe the developing conceptus.1
This transition marks the end of the embryonic periodāa phase primarily defined by organogenesisāand the beginning of the fetal period, which is characterized by the maturation of tissues and organs and rapid body growth.2