Everything You Need To Know About Prenatal Development

The following excellent video is from Abort73.com



The EHD - The Endowment For Human Development created the best description of prenatal development that I have seen.  Please click on each stage to watch what they call The Movie Theater of the different levels of development.

0-2 Weeks
Approximately 24 to 30 hours after fertilization, the zygote completes its first cell division. Through the process of mitosis, one cell splits into two, two into four, and so on.

2-4 Weeks
Following implantation, cells on the periphery of the blastocyst give rise to part of a structure called the placenta, which serves as an interface between the maternal and embryonic circulatory systems.

The placenta delivers maternal oxygen, nutrients, hormones, and medications to the developing human; removes all waste products; and prevents maternal blood from mixing with the blood of the embryo and fetus.  The placenta also produces hormones and maintains embryonic and fetal body temperature slightly above that of the mother's.  The placenta communicates with the developing human through the vessels of the umbilical cord.

4-6 Weeks
By 4 weeks the clear amnion surrounds the embryo in a fluid-filled sac. This sterile liquid, called amniotic fluid, provides the embryo with protection from injury.

6-8 Weeks
By 6 weeks the cerebral hemispheres are growing disproportionately faster than other sections of the brain. The embryo begins to make spontaneous and reflexive movements. Such movement is necessary to promote normal neuromuscular development.

8-10 Weeks
By 8 weeks, 75% of embryos exhibit right-hand dominance. The remainder is equally divided between left-handed dominance and no preference. This is the earliest evidence of right- or left-handed behavior.

10-12 Weeks
By 10 weeks, stimulation of the upper eyelid causes a downward rolling of the eye.  The fetus yawns and often opens and closes the mouth.

3-6 Months
Between 11 and 12 weeks, fetal weight increases nearly 60%.  Twelve weeks marks the end of the first third, or trimester, of pregnancy.

6-9 Months
By 24 weeks the eyelids reopen and the fetus exhibits a blink-startle response. This reaction to sudden, loud noises typically develops earlier in the female fetus.