The neural tube will become the brain and spinal cord, but at first the neural tube is hollow and open at both ends. During the fourth week of prenatal development, the neural tube begins to close. This is an especially critical time for development because the failure of the neural tube to close at either end causes neural tube defects like spina bifida and anencephaly. Spina bifida occurs when the bottom part of the neural tube fails to close. The nerves of the spinal cord grow outside of the protective vertebrae and require surgery to reroute the nerves immediately after birth.
Some damage usually remains including bladder problems and sometimes paralysis.
A baby with anencephaly is born with all or parts of the cerebral cortex missing and usually dies shortly after birth. Research shows that folic acid, a form of vitamin B, prevents neural tube defects. Because neural tube defects are so devastating and preventable, proper nutrition is essential early in pregnancy. Pregnant women should take .8 to 1mg of folic acid each day to prevent neural tube defects. The embryo contains all of the organs that a newborn baby will have.