Prenatal Brain Development: From Conception to Birth

I absolutely love babies and I've always been fascinated with fetuses, ever since I saw pictures in my health book in high school.  I thought the fetuses were cute and how they developed was pretty amazing.  When I read the the text, I noticed that the book didn't go into much detail other than Figure 5.1 and 5.2, which shows how the CNS is developed and the brain at the 4 stages.

In the first trimester of a pregnancy, the neural tube forms from the neural plate, which folds over onto itself.  At four weeks, the neural tube will become the forebrain, midbrain, hindbrain and spinal cord of the fetus.  "By week 7, the first neurons and synapses have formed and allow the fetus to make its first movements and allow the brain to develop sensory input," UCI.  Week 8 is the last of the embryonic stage and by this point, the hindbrain has began to regulate the fetus' breathing and heartbeat.  It is crucial that no alcohol, drugs, or smoking be done during this period of the embryonic stage (conception to 8 weeks), since the fetus is growing rapidly.

In weeks 9 and 10 (fetal stage), the nervous system is functioning and the brain is forming 250,000 neurons per minute!  From weeks 9 to 12, the fetus has reflexes, the baby moves without the mother feeling it, the sex organs develop, and the spinal cord has nerves that allow movement.  Myelination also occurs, as well as the presence of gyri and sulci on the brain in the second trimester.

I chose this video because it goes more into detail on what occurs during the prenatal development of the brain.  It states that, "Between week 8 and 26, the cerebral cortex grows to cover the midbrain.  By week 28, the cortex increases in surface area, becomes wrinkled, and folds in the skull."

From weeks 19-26, the fetus has developed motor neurons and the mother will be able to feel the fetus kicking and moving around, cute, right?  By this time, the nervous system is joining together, the auditory and visual systems are heightened, and if a light is shined on the mother's belly, the fetus will try to shield their eyes.  That's adorable!

The rest of the trimester, the baby continues to develop at a slower rate and can distinguish certain sounds, songs, and recognize the mother's voice.  All of this takes place in about 40 weeks and a newborn's brain is only a quarter size of an adult's!