A: Folic acid (a B vitamin) is already included in prenatal vitamin formulas. So the question is whether it's safe to take additional folic acid if you're already taking a prenatal vitamin.

If your doctor has advised you to take supplemental folic acid in addition to a prenatal vitamin, find out whether there are specific features of your pregnancy that makes this advisable. If there are no special reasons to take extra folic acid, your prenatal vitamin supplement should provide sufficient folic acid for a healthy pregnancy.

Remember, all women of childbearing age are advised to take 400 micrograms (mcg) of folic acid a day in addition to what they get through their diet. This reduces the risk of neural tube birth defects by 70 percent. Higher doses (4 milligrams, equal to 4,000 micrograms) of folic acid are recommended if you or another family member already had a baby with a neural tube defect, or if you have diabetes or epilepsy. However, in low-risk situations, taking more than 1,000 micrograms (1 milligram) of supplemental folic acid is not generally advised. This is because high doses can mask another medical condition, pernicious anemia, which results from a vitamin B12 deficiency.