[Folic acid supplementation by 200 microgram per day during the periconceptional period: a necessary public health approach to reducing incidence of spina bifida].

The incidence of neural tube closure abnormalities, and particularly Spina-bifida is correlated with a low dietary intake of folic acid, for which the marker is the erythrocyte folate concentration. Initially, preventive policies concerned women treated with anticonvulsant agents and those with a known family history of Spina-bifida. This constituted secondary prevention.