When should folic acid supplementation start in order to be effective in preventing neural tube defects?

Ans. C. At least one month before conception* To be effective, folic acid supplementation should be started at least 1 month before conception, and continued through the first 2-3 months of pregnancy.* All women desirous of becoming pregnant should consume 400-800mg folic acid daily; the dose is 4mg/day in those having delivered a child with neural tube defect.