<prompt> A lady has history of previous child birth with neural tube defect. What is the dose of folic acid to be given to prevent to neural tube defect in this child4000 mcg in periconceptional period400 mg after confirmation of pregnancy400 mg in periconceptional period4000 mcg in 1st 2nd trimester.  <response>: Dose of folic acid for primary prevention is 400 mcg dayDose of folic acid for secondary prevention prevoius child affected with neural tube defect is 4000 mcg day started in periconception period 1 month before to 3 months after conception. 