What is the medical benefit of folic acid for pregnant women?

Prevent Spina Bifida. Folic acid is extremely important during pregnancy to prevent spina bifida, a condition in which the spinal vertebrae do not close properly and the spinal cord is not protected. There are several types of spina bifida, all of which can be prevented with folic acid. Folic acid is also important for making dna and development of the neurological system - especially the spinal cord and vertebrae.
Folic acid supplemen. It is estimated that 50-70% of cases of spina bifida and other neural tube defects could be prevented if all women of child-bearing age took 400 micrograms (0.4mg) of Folic Acid daily. Because neural tube defects develop during the first 3 to 4 weeks after conception, it is usually too late for a woman to start taking a Folic Acid supplement after she becomes pregnant.
Prevent spina bifida. Folic acid is needed for the development of a normal spinal column. See previous answer.