Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Neural Tube Defects ?
    ### Response:
    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the first month of pregnancy, often before a woman even knows that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In spina bifida, the fetal spinal column doesn't close completely.
    