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Prenatal Development & Birth
- From Zygote to Newborn -

Ψ  The Germinal Period: From the moment of conception until 14 days later. The first 7- 10 days constitute a dangerous journey as the zygote moves down the fallopian tube to implantation in the uterus where it can be nourished. Rapid cell division & the beginning of cell differentiation follows.

Ψ  The Period of the Embryo: From 14 days until 56 days after conception. During this time all major external & internal body structures begin to form.

Ψ  The Period of the Fetus: From the ninth week after conception until birth. Age of viability (about 22 weeks).

    Note: The brain increases about six times in size & develops many new neurons (neurogenesis) & synapses (synaptogenesis) in the middle trimester (4 to 6 months).

It's a Mickey Mouse World , isn't it?

Ψ  Vulnerability During Prenatal Development

    The Germinal Period: About 60% of all developing organisms fail.

    The Period of the Embryo: About 20% of embryos are aborted spontaneously.

    The Period of the Fetus: About 5% of all fetuses are lost.

    Birth: About 31% of all zygotes (conceptions) grow & survive.

Growth & Development
Robert C. Gates