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How does the fetal period differ from the earlier embryonic period?
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human development
Growth of the human fetus from the fourth month to the ninth month of pregnancy.
In human prenatal development, the embryonic and fetal periods are distinguished by their primary biological focus and timing.1
- Embryonic Period: Lasting from the third to the eighth week after conception, this stage is defined by organogenesis, the process during which the basic structures and organ systems of the body are formed. By the end of this period, the embryo has attained the fundamental form and structure typical of a human.12
- Fetal Period: Beginning around the eighth week and continuing until birth, this stage is characterized by the maturation of tissues and organs, as well as rapid body growth. While the embryonic phase focuses on the creation of new structures, the fetal period emphasizes the full development and functional refinement of those established systems.12
Essentially, while the embryonic period establishes the body's blueprint, the fetal period is dedicated to the growth and physiological preparation necessary for life outside the womb.12