Early Development
The fetus begins to develop brain tissue during the fourth week of pregnancy. At first, the neural tube grows from the ectoderm or outside layer of the embryo and by week 6, the neural tube closes to begin brain formation. During week 10, 250,000 new neurons will be produced every minute within the developing brain. Soon after, the fetus will be able to use her developing brain to move her tiny body, swallow, suck and smell.
Later Development
During the second trimester, the brain continues to develop and starts making connections with other parts of the body. By week 18, the brain is able to interpret sounds heard from the ears and by the end of this trimester, the fetus will be able to recognize its mother's voice. By week 19, the brain's motor neurons enable to fetus to have reflexive movements. At week 22, the brain is able to respond to the sense of touch. By the end of the second trimester, the fetus can see light. During the third trimester, the fetal brain continues to grow and make connections.
Developmental Impairments
Drinking alcohol during pregnancy can have very harmful effects on the developing fetal brain. Alcohol consumption has been linked to learning disabilities, language impairments and ADHD. In severe cases, a fetus exposed to excess alcohol may be born with fetal alcohol syndrome. Smoking tobacco during pregnancy has also been linked to developmental problems, including learning disabilities and behavioral problems.
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