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From Zygote To Fetus: The Stages Of Prenatal Development

    From Zygote To Fetus: The Stages Of Prenatal Development

    It’s amazing how we, grown adults that we are, came from a single-cell structure. Our development before birth (prenatal development) is a delicate process that happens in an orderly fashion. Here’s what you need to know about the stages of prenatal development.

    Prenatal Development Is Critical For The Child’s Future Health

    The stages of prenatal development are germinal, embryonic, and fetal. Please note that these stages are not the same as the three trimesters of pregnancy.

    Prenatal development sets the stage for the child’s future health. If something goes wrong in the first stage, the second and third stage might get affected, further leading to future health problems or even death.

    The Stages of Prenatal Development

    What happens during each stage of prenatal development?

    Stage 1: Germinal Stage

    The germinal stage occurs from the moment of conception when the sperm cell fertilizes the egg cell to form the zygote, to the time when this single-cell structure implants itself into the uterine lining.

    During this stage:

    • The baby’s genetic makeup is set. Their sex is also determined although parents wouldn’t know it until months later.
    • The single-cell zygote divides continuously. By the 5th day of cell division, cell differentiation happens. This is the formation of specialized cells that will form the different organs.
    • About a week to 10 days later, the multicellular structure which will become the embryo will implant itself into the lining of the uterus.

    The germinal stage is a critical period. It is said that less than 50% of zygotes survive the first two weeks. About 60% also fail to attach to the uterus. At this point, the mother is often not aware that she is pregnant.

    Stage 2: Embryonic Stage

    Second in the stages of prenatal development is the embryonic stage, which lasts from the 3rd to the 8th week. Once the zygote implants itself into the uterine lining, we now call it an embryo.

    During this stage:

    • The placenta, an organ where the embryo/fetus will get their nourishment, forms.
    • The basic areas that will become the head, chest, and abdomen forms.
    • Some organs form and begin to function.
    • The heart beats.
    • At this point, too, the neural tube forms. This will become the spinal cord and brain.
    • The embryo can move and even respond to touch.

    Reports say about 20% of embryos fail at this stage, significantly due to chromosomal abnormalities. And just like in the germinal stage, the mother may not be aware that she is already pregnant.


    Because the mother may not be aware that she is pregnant during the germinal and embryonic stage, she might engage in activities that may endanger her and her baby’s health, like substance abuse and cigarette smoking. Hence, it would be helpful to be aware of the early signs of pregnancy.

    Stage 3: The Fetal Stage

    The fetal period is from the 9th to the 40th week. By the 9th week, too, we no longer call it an embryo but a fetus.

    During this stage:

    • The fetus has all its body parts, including the sex organs, which means parents can now identify the sex.
    • Their fingerprints also become visible.
    • Some of the reflexes, like sucking and swallowing, develop.
    • The fetus can now respond to sounds.

    Generally, the development of the fetus continues and the changes that development brings become more visible.

    Key Takeaways

    While many people are familiar with the three trimesters of pregnancy, seldom take note of the stages of prenatal development.

    Prenatal development is a delicate process that occurs in sequenced stages, namely germinal, embryonic, and fetal. Generally, issues arising in any of these stages may result in long-term problems or even death, especially in the germinal and embryonic stages as well as the early part of the fetal stage.

    Learn more about Pregnancy here.


    Due Date Calculator

    Use this calculator to find your due date. This is just an estimate – not a guarantee! Most women, but not all, will deliver their babies within a week before or after this date range.

    Cycle Length

    28 days

    Hello Health Group does not provide medical advice, diagnosis or treatment.

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    Written by Lorraine Bunag, R.N. Updated Jun 22
    Fact Checked by Kristel Lagorza
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