What is the difference between embryo and fetus

What is the difference between embryo and fetus

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The gestation period It consists of three main stages, the first refers to the zygote, the second to the embryonic period and the third to the fetal stage. Many are the people who have difficulties to differentiate them and to know for sure when the baby goes from being an embryo to a fetus. Therefore, in this OneHowTo article we want to resolve this question and show you what both processes consist of. Keep reading and discover what is the difference between embryo and fetus.


After 24 hours of the union between the ovum and the sperm, the second stage of gestation begins, called embryonic period. This is when the creation and development of the embryo occurs. This period is also characterized by going through different stages until concluding and giving rise to the fetus.

During the first five days, when the two cells that start the formation of the embryo begin to divide and create more cells to the point of not being able to differentiate them clearly, it is called an embryo in a morula state. After five days, it is called a blastocyst. At this point in gestation the embryo has Round shape and begins to create an internal cavity that will allow the formation of the placenta and the rest of the body of the future baby. The first days of the blastocyst are the most important since it is when it must be fixed in the mother’s uterus and start the pregnancy process. Normally this implantation process ends 14 days after fertilization.

Once implanted, it will begin to grow and develop rapidly, so that it will acquire an elongated shape similar to that of a baby. From the eighth week of pregnancy, the future baby already has all the organs and begins to develop the limbs, this is when the fetal stage begins and the embryo becomes a fetus.

What is the difference between embryo and fetus - Embryo

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As specified in the previous section, once the 8th week of the gestation period has been reached, we no longer speak of an embryo but a fetus, because the future baby already has all the internal organs, although not fully developed, and begins to form the arms, legs and fingers. From this moment on, the baby will be considered fetus until born, so it is the longest stage of pregnancy.

What is the difference between embryo and fetus - Fetus

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Differences between embryo and fetus

Once the definitions of both stages of pregnancy have been explained, the differences between embryo and fetus are as follows:

  • Embryo is the name that the future baby receives from fertilization to the first 8 weeks of pregnancy.
  • From 8 weeks of pregnancy to the day of birth, the baby is a fetus, not an embryo.
  • The fetus has all the internal organs while the embryo is still developing them.
  • The fetus begins to form the limbs until it acquires the complete shape of the baby.
  • The embryo does not have all defined body parts.

This article is merely informative, at oneHOWTO we do not have the power to prescribe any medical treatment or make any type of diagnosis. We invite you to see a doctor in the case of presenting any type of condition or discomfort.

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