In a lady with history of bih of a previous child with neural tube defect, amount of folic acid to be given in microgram as secondary prophylaxis before next conception is:

To prevent NTDs, it is recommended that all women of child-bearing age, who are capable of becoming pregnant should take 0.4 mg (400 mg) of folic acid daily. If a pregnancy is planned in high risk women (with previously affected child), supplementation should be staed with 4 mg (4000 mg) of folic acid daily, beginning 1 month before the time of the planned conception.