<prompt> Folic acid required in first trimester of normal pregnancy -100 microgram400 microgram4 mg5 mg  <response>: Ans. is b i.e., 400 microgram Some NTDs are associated with a specific mutation in the methylene tetrahydrofolate reductase gene, the adverse effects of which can be largely overcome by periconceptional folic acid supplementation. More than half of NTDs could be prevented with daily intake of 400 pgm of folic acid throughout the periconceptional period. A woman with a prior pregnancy complicated by a neural tube defect can reduce the 23 recurrence risk by more than 70 if she takes 4 mg of folic acid for the month before conception and for the first trimester of pregnancy. 