Neural tube defects and periconceptional folic acid in England and Wales: retrospective study   Commentary: Food should be fortified with folic acid

The risks of a first occurrence and a recurrence of neural tube defects have been shown to be reduced by periconceptional folic acid supplementation-that is by taking folic acid from 3 months before conception to 3 months after conception. 1 2 The Expert Advisory Group in the United Kingdom recommended in 1992 that women who were trying to conceive should take 0.4 mg folic acid per day. 3 We assessed whether there had been any change in the incidence of neural tube defects since this recommendation was made.