What is the use of folic acid in general?

Cell division: Adequate folate (folic acid) is essential for cell division, due to its role in the synthesis of nucleic and certain amino acids. Folate (folic acid) deficiency may interfere with adequate cell turnover during a critical point in the closure of the neural tube. The only well-established benefit of Folic Acid supplementation is the prevention of neural tube defects in fetal development.

Pregnancy/Anemia: Folic acid, AKA folate (folic acid) (vit B9), is recommended for all women wanting to get pregnant -- 0.4mg (400mcg) daily, which is important for preventing birth defects like spina bifida. Women w/ a hx these disorders should take 10x that amt daily -- 4mg (4000mcg) through the 3rd month of pregnancy. It won't affect fertility, chances of conception/twins, or periods. Can help with anemia.