All women who may become pregnant should take a daily supplement of 400 to 800 micrograms of folic acid, not just those who are pregnant or planning to become pregnant, according to the latest recommendation from the U.S. Preventive Services Task Force. This reaffirms the influential group’s previous guidelines; nearly all other medical groups advise at least 400 micrograms.
Folic acid, the form of the B vitamin folate used for supplements and in fortified foods, greatly reduces the risk of neural tube birth defects. The critical period for supplementation starts one month before conception and continues through the first trimester.
Since half of all pregnancies are unplanned, all women who are capable of becoming pregnant should take folic acid, just in case. It’s hard to get this much folate from food; in addition, folic acid is better absorbed by the body than the folate naturally in food.
Most multivitamins contain 400 micrograms of folic acid. It’s estimated that fewer than one-third of women of childbearing age are taking folic acid.
Also see Do You Need a Multivitamin?