During pregnancy, you need large quantities of folic acid to help ensure that you're meeting the needs of your developing embryo or fetus. Generally speaking, 800 micrograms of folic acid is not too much -- in fact, your obstetrician may advise you take as much as 1000 micrograms of folic acid daily during pregnancy.
Folic acid is one of the B vitamins that, when you're not pregnant, is important to helping your cells engage in the reactions of energy-processing. During pregnancy, it becomes even more important than it normally is because folic acid helps provide for proper development of the neural tube. This is a structure that becomes the brain and spinal cord.
Folic Acid Deficiency
Because folic acid isn't one of the most common vitamins in food sources, it's quite common for women of childbearing age to be deficient in the vitamin, particularly with regard to the increased needs of pregnancy. If you're deficient in folic acid during the early days and weeks of pregnancy, your baby has a greatly increased risk of birth defects involving the spinal cord, particularly spina bifida.
To help prevent folic acid deficiencies -- and other vitamin and mineral deficiencies -- many obstetricians recommend that you take a prenatal vitamin during pregnancy. This is a multivitamin and mineral supplement specially formulated for the needs of pregnant women and their developing fetuses, and typically includes 800 to 1000 micrograms of folic acid. If you choose not to take a prenatal vitamin, you should at least use a separate folic acid supplement.
One of the things you may want to take into account when you begin to consider becoming pregnant is that the neural tube develops very early in pregnancy -- around six weeks of gestational age. Six weeks gestational age is only four weeks after you conceived, and only about two weeks after your expected period, meaning you may not yet know you're pregnant. For this reason, many women take supplemental folic acid -- 800 to 1000 micrograms per day -- throughout their childbearing years.